stb_ds.h: fix unused parameter warning

stb_ds.h

@@ -447,6 +447,12 @@ CREDITS
 #define STBDS_FREE(c,p)      free(p)
 #endif
 
+#ifdef _MSC_VER
+#define STBDS_NOTUSED(v)  (void)(v)
+#else
+#define STBDS_NOTUSED(v)  (void)sizeof(v)
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -827,6 +833,7 @@ void stbds_rand_seed(size_t seed)
 
 static size_t stbds_probe_position(size_t hash, size_t slot_count, size_t slot_log2)
 {
+  STBDS_NOTUSED(slot_log2);
   size_t pos;
   pos = hash & (slot_count-1);
   #ifdef STBDS_INTERNAL_BUCKET_START
@@ -1166,6 +1173,7 @@ size_t stbds_hash_bytes(void *p, size_t len, size_t seed)
 
 static int stbds_is_key_equal(void *a, size_t elemsize, void *key, size_t keysize, size_t keyoffset, int mode, size_t i)
 {
+  STBDS_NOTUSED(keyoffset);
   if (mode >= STBDS_HM_STRING)
     return 0==strcmp((char *) key, * (char **) ((char *) a + elemsize*i));
   else