stdlib doesnt' compile with gcc-15

[dopefishh]

Once it builds, I'll make a PR for the fixes.

For example:

[ 22%] Generating /home/mrl/projects/sac/Stdlib/build/src-seq/system/src/GetOpt/getopt.o for target `seq'
/home/mrl/projects/sac/Stdlib/src/system/src/GetOpt/getopt.c: In function ‘getopt_sac’:
/home/mrl/projects/sac/Stdlib/src/system/src/GetOpt/getopt.c:150:20: error: assignment discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
  150 |                 (p = strchr(opts, SAC_optopt)) == NULL) {
      |                    ^
At top level:
cc1: note: unrecognized command-line option ‘-Wno-comma’ may have been intended to silence earlier diagnostics
cc1: note: unrecognized command-line option ‘-Wno-gnu-line-marker’ may have been intended to silence earlier diagnostics
cc1: note: unrecognized command-line option ‘-Wno-c2x-compat’ may have been intended to silence earlier diagnostics
cc1: all warnings being treated as errors
Abort:
  System failed to execute shell command
  /usr/bin/cc  -I.  -DHAVE_CONFIG_H -I/home/mrl/projects/sac/Stdlib/build/include
  -I/home/mrl/projects/sac/Stdlib/include -DFULLTYPES -DEXT_STDLIB
  -I/home/mrl/projects/sac/Stdlib/src/system/src/GetOpt
  -I/home/mrl/projects/sac/Stdlib/build/src-seq/system/src/GetOpt
  -I/usr/local/include/sac2c/2.0.0-Tintigny-539-gbc59b-dirty/debug
  -I/home/mrl/projects/sac/sac2c/build_d/runtime_build/src/runtime_libraries-build/include
  -I/home/mrl/projects/sac/sac2c/build_d/include -I/home/mrl/projects/sac/sac2c/include
  -I/home/mrl/projects/sac/sac2c/build_d/runtime_build/src/runtime_libraries-build/include
  -I/home/mrl/projects/sac/sac2c/build_d/include -I/home/mrl/projects/sac/sac2c/include
  -I/home/mrl/projects/sac/sac2c/build_d/runtime_build/src/runtime_libraries-build/include
  -I/home/mrl/projects/sac/sac2c/build_d/include -I/home/mrl/projects/sac/sac2c/include
  -DSAC_TARGET_seq -DSAC_INT="int64_t" -DPRIisac="PRId64" -DSAC_TARGET_STRING=\"seq\"
  -DSAC_MODEXT_STRING=\".so\" -DSAC_TARGET_ENV_STRING=\"host\" -DSAC_SBI_STRING=\"seq\"
  -DSAC_RC_METHOD=SAC_RCM_local -DSAC_BACKEND_C99 -DSAC_MT_LIB_ -DSAC_SHRAY_LIB_ -DSAC_MT_MODE=0
  -DSAC_DO_RTSPEC=0 -DSAC_DO_CUDA_ALLOC=SAC_CA_system -DSAC_DO_CUDA_SYNC=1 -O3 -ffast-math
  -march=native -mtune=native  -pedantic -g -fPIC -D_POSIX_C_SOURCE=200809L -D_DEFAULT_SOURCE
  -D_SVID_SOURCE -D_BSD_SOURCE  -Wno-alloc-size -Wno-use-after-free -Wall -Wextra -Werror -pedantic
  -fopenmp -Wno-free-nonheap-object -Wno-unused -Wno-sign-compare -fno-builtin-malloc
  -Wno-tautological-compare -Wno-array-bounds -Wno-strict-overflow -pedantic -fopenmp  -Wno-c2x-compat
  -Wno-gnu-line-marker -Wno-stringop-overflow -Wno-comma -Wno-unreachable-code -c -o
  /home/mrl/projects/sac/Stdlib/build/src-seq/system/src/GetOpt/getopt.o
  /home/mrl/projects/sac/Stdlib/src/system/src/GetOpt/getopt.c
  with exit code 1
Compilation failed while initial.
make[2]: *** [src-seq/CMakeFiles/seq-module-GetOpt.dir/build.make:85: src-seq/system/src/GetOpt/getopt.o] Error 255
make[1]: *** [CMakeFiles/Makefile2:1244: src-seq/CMakeFiles/seq-module-GetOpt.dir/all] Error 2