Fixed broken VFS support, linking issues (#899)

* VFS fix

* Linking errors

* MSVC comoile fix

deps/libchdr/include/libchdr/coretypes.h

@@ -20,22 +20,31 @@ typedef int32_t INT32;
 typedef int16_t INT16;
 typedef int8_t INT8;
 
+#ifdef USE_LIBRETRO_VFS
+#define core_file RFILE
+#define core_fopen(file) rfopen(file, "rb")
+#define core_fseek rfseek
+#define core_ftell rftell
+#define core_fread(fc, buff, len) fread(buff, 1, len, fc)
+#define core_fclose rfclose
+#else /* USE_LIBRETRO_VFS */
 #define core_file FILE
 #define core_fopen(file) fopen(file, "rb")
 #if defined(__WIN32__) || defined(_WIN32) || defined(WIN32) || defined(__WIN64__)
-	#define core_fseek _fseeki64
-	#define core_ftell _ftelli64
+#define core_fseek _fseeki64
+#define core_ftell _ftelli64
 #elif defined(_LARGEFILE_SOURCE) && defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64
-	#define core_fseek fseeko64
-	#define core_ftell ftello64
+#define core_fseek fseeko64
+#define core_ftell ftello64
 #else
-	#define core_fseek fseeko
-	#define core_ftell ftello
+#define core_fseek fseeko
+#define core_ftell ftello
 #endif
 #define core_fread(fc, buff, len) fread(buff, 1, len, fc)
 #define core_fclose fclose
+#endif /* USE_LIBRETRO_VFS */
 
-static UINT64 core_fsize(core_file *f)
+static UINT64 core_fsize(core_file* f)
 {
     UINT64 rv;
     UINT64 p = core_ftell(f);

libretro.cpp

@@ -56,7 +56,10 @@ retro_input_state_t dbg_input_state_cb = 0;
 #endif /* HAVE_LIGHTREC */
 
 //Fast Save States exclude string labels from variables in the savestate, and are at least 20% faster.
-extern bool FastSaveStates;
+extern "C" {
+    extern bool FastSaveStates;
+}
+
 const int DEFAULT_STATE_SIZE = 16 * 1024 * 1024;
 
 static bool libretro_supports_option_categories = false;
@@ -113,7 +116,7 @@ int memfd;
 #endif
 #endif
 
-uint32 EventCycles = 128;
+int32 EventCycles = 128;
 uint8_t spu_samples = 1;
 
 // CPU overclock factor (or 0 if disabled)

mednafen/clamp.h

@@ -10,6 +10,10 @@ extern "C" {
 #include <unistd.h>
 #endif
 
+#ifdef _MSC_VER
+#include <compat/msvc.h>
+#endif
+
 static INLINE void clamp(int32_t *val, ssize_t min, ssize_t max)
 {
    if(*val < min)