Start a contrib/ with libgc and libregex (#127)

contrib/README.md

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+# Unsupported w64devkit enhancements
+
+The files in this directory enhance w64devkit with specially-built
+third-party libraries, such as garbage collection and POSIX `regex.h`.
+Falling outside the scope of w64devkit, these libraries are not included
+in the distribution, but may be situationally useful.
+
+The header of each file has the instructions for its use. The file itself
+is mostly a custom build script, and you will need to obtain the library
+sources yourself the usual way.

contrib/libgc.c

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+#if 0
+# Minimalist, stripped down, w64devkit, static, unity build of Boehm GC.
+# Provides an easy-to-use garbage collector weighing ~24KiB. The API is
+# two functions: GC_malloc and GC_realloc. Tested with gc 8.2.4.
+#
+# Place this source file in the Boehm GC source tree root, then invoke
+# it with the shell to produce gc.h and libgc.a.
+#
+#     $ sh libgc.c
+#
+# Philosophy: If the goal is ease-of-use, remove all knobs that are not
+# strictly necessary. If performance isn't good enough, don't use garbage
+# collection; switch to a region-based allocator.
+#
+# Ref: https://www.hboehm.info/gc/gc_source/gc-8.2.4.tar.gz
+# This is free and unencumbered software released into the public domain.
+set -ex
+
+PREFIX="${PREFIX:-$(gcc -print-sysroot)}"
+
+${CC:-cc} -c -Iinclude -fwhole-program ${CFLAGS:--Os} libgc.c
+${STRIP-strip} -x libgc.o
+
+mkdir -p "$PREFIX/lib"
+rm -f "$PREFIX/lib/libgc.a"
+${AR:-ar} -r "$PREFIX/lib/libgc.a" libgc.o
+
+mkdir -p "$PREFIX/include"
+tee "$PREFIX/include/gc.h" <<EOF
+#ifndef GC_H
+#define GC_H
+// Single-threaded, garbage-collected, zero-initialized memory allocation.
+#include <stddef.h>
+void *GC_malloc(size_t)          __attribute((alloc_size(1), malloc));
+void *GC_realloc(void *, size_t) __attribute((alloc_size(2)));
+#endif
+EOF
+exit 0
+#endif
+
+#define ALL_INTERIOR_POINTERS
+#define DONT_USE_ATEXIT
+#define GC_API
+#define GC_NO_FINALIZATION
+#define GC_TOGGLE_REFS_NOT_NEEDED
+#define GC_USE_ENTIRE_HEAP
+#define NO_CLOCK
+#define NO_DEBUGGING
+#define NO_GETENV
+#define NO_MSGBOX_ON_ERROR
+
+#include "allchblk.c"
+#include "alloc.c"
+#include "blacklst.c"
+#include "dbg_mlc.c"
+#include "dyn_load.c"
+#include "finalize.c"
+#include "headers.c"
+#include "mach_dep.c"
+#include "malloc.c"
+#include "mallocx.c"
+#include "mark.c"
+#include "mark_rts.c"
+#include "misc.c"
+#include "new_hblk.c"
+#include "obj_map.c"
+#include "os_dep.c"
+#include "ptr_chck.c"
+#include "reclaim.c"
+
+__attribute((used)) void *GC_malloc(size_t);
+__attribute((used)) void *GC_realloc(void *, size_t);

contrib/libregex.c

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+#if 0
+# Stripped down, w64devkit, static, unity build of the PCRE2 POSIX regex
+# library. This script builds and installs regex.h and libregex.a inside
+# w64devkit. Link with -lregex. It is pretty bulky, nearly 300KiB.
+#
+# Copy and run this script in the root fo the PCRE source tree. Tested
+# with PCRE 10.43.
+#
+#     $ sh libregex.c
+#
+# Ref: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/regex.h.html
+# This is free and unencumbered software released into the public domain.
+set -ex
+
+PREFIX="${PREFIX:-$(gcc -print-sysroot)}"
+
+cp src/pcre2.h.generic src/pcre2.h
+${CC:-cc} -c -fwhole-program ${CFLAGS:--Os} "$0"
+${STRIP:-strip} -x libregex.o
+
+mkdir -p "$PREFIX/lib"
+rm -f "$PREFIX/lib/libregex.a"
+${AR:-ar} -r "$PREFIX/lib/libregex.a" libregex.o
+
+mkdir -p "$PREFIX/include"
+tee >nul $PREFIX/include/regex.h <<EOF
+#pragma once
+#include <stddef.h>
+
+enum {
+    REG_EXTENDED = 0x0000,
+    REG_ICASE    = 0x0001,
+    REG_NEWLINE  = 0x0002,
+    REG_NOTBOL   = 0x0004,
+    REG_NOTEOL   = 0x0008,
+    REG_DOTALL   = 0x0010,
+    REG_NOSUB    = 0x0020,
+    REG_UTF      = 0x0040,
+    REG_STARTEND = 0x0080,
+    REG_NOTEMPTY = 0x0100,
+    REG_UNGREEDY = 0x0200,
+    REG_UCP      = 0x0400,
+    REG_PEND     = 0x0800,
+    REG_NOSPEC   = 0x1000,
+};
+
+enum {
+    REG_ASSERT = 1,
+    REG_BADBR,
+    REG_BADPAT,
+    REG_BADRPT,
+    REG_EBRACE,
+    REG_EBRACK,
+    REG_ECOLLATE,
+    REG_ECTYPE,
+    REG_EESCAPE,
+    REG_EMPTY,
+    REG_EPAREN,
+    REG_ERANGE,
+    REG_ESIZE,
+    REG_ESPACE,
+    REG_ESUBREG,
+    REG_INVARG,
+    REG_NOMATCH,
+};
+
+typedef struct {
+    void  *re_pcre2_code;
+    void  *re_match_data;
+    char  *re_endp;
+    size_t re_nsub;
+    size_t re_erroffset;
+    int    re_cflags;
+} regex_t;
+
+typedef int regoff_t;
+
+typedef struct {
+    regoff_t rm_so;
+    regoff_t rm_eo;
+} regmatch_t;
+
+int    regcomp(regex_t *, const char *, int);
+size_t regerror(int, const regex_t *, char *, size_t);
+int    regexec(const regex_t *, const char *, size_t, regmatch_t *, int);
+void   regfree(regex_t *);
+EOF
+exit 0
+#endif
+
+#define PCRE2_EXP_DEFN          static
+#define PCRE2_EXP_DECL          static
+#define PCRE2POSIX_EXP_DECL
+#define PCRE2POSIX_EXP_DEFN     __attribute((used))
+
+#define HAVE_BUILTIN_MUL_OVERFLOW
+#define HAVE_MEMMOVE
+#define HEAP_LIMIT              20000000
+#define LINK_SIZE               2
+#define MATCH_LIMIT		        10000000
+#define MATCH_LIMIT_DEPTH	    MATCH_LIMIT
+#define MAX_NAME_COUNT	        10000
+#define MAX_NAME_SIZE	        32
+#define MAX_VARLOOKBEHIND       255
+#define NEWLINE_DEFAULT         2
+#define PARENS_NEST_LIMIT       250
+#define PCRE2_CODE_UNIT_WIDTH   8
+#define PCRE2_STATIC
+#define SUPPORT_UNICODE
+
+#include "src/pcre2posix.h"
+#undef  regcomp
+#undef  regexec
+#undef  regerror
+#undef  regfree
+#define pcre2_regcomp   regcomp
+#define pcre2_regexec   regexec
+#define pcre2_regerror  regerror
+#define pcre2_regfree   regfree
+#include "src/pcre2posix.c"
+
+#include "src/pcre2_auto_possess.c"
+#include "src/pcre2_chartables.c.dist"
+#include "src/pcre2_chkdint.c"
+#include "src/pcre2_compile.c"
+#include "src/pcre2_context.c"
+#include "src/pcre2_extuni.c"
+#include "src/pcre2_find_bracket.c"
+#include "src/pcre2_match.c"
+#include "src/pcre2_match_data.c"
+#include "src/pcre2_newline.c"
+#include "src/pcre2_ord2utf.c"
+#include "src/pcre2_pattern_info.c"
+#include "src/pcre2_script_run.c"
+#include "src/pcre2_string_utils.c"
+#include "src/pcre2_study.c"
+#include "src/pcre2_tables.c"
+#include "src/pcre2_ucd.c"
+#include "src/pcre2_valid_utf.c"
+#include "src/pcre2_xclass.c"