change previous explicitly-sized realloc support to be new API and unbreak old API

stb_image.h

@@ -621,18 +621,22 @@ typedef unsigned char validate_uint32[sizeof(stbi__uint32)==4 ? 1 : -1];
    #define stbi_lrot(x,y)  (((x) << (y)) | ((x) >> (32 - (y))))
 #endif
 
-#if defined(STBI_MALLOC) && defined(STBI_FREE) && defined(STBI_REALLOC)
+#if defined(STBI_MALLOC) && defined(STBI_FREE) && (defined(STBI_REALLOC) || defined(STBI_REALLOC_SIZED))
 // ok
-#elif !defined(STBI_MALLOC) && !defined(STBI_FREE) && !defined(STBI_REALLOC)
+#elif !defined(STBI_MALLOC) && !defined(STBI_FREE) && !defined(STBI_REALLOC) && !defined(STBI_REALLOC_SIZED)
 // ok
 #else
-#error "Must define all or none of STBI_MALLOC, STBI_FREE, and STBI_REALLOC."
+#error "Must define all or none of STBI_MALLOC, STBI_FREE, and STBI_REALLOC (or STBI_REALLOC_SIZED)."
 #endif
 
 #ifndef STBI_MALLOC
-#define STBI_MALLOC(sz)             malloc(sz)
-#define STBI_REALLOC(p,oldsz,newsz) realloc(p,newsz)
-#define STBI_FREE(p)                free(p)
+#define STBI_MALLOC(sz)           malloc(sz)
+#define STBI_REALLOC(p,newsz)     realloc(p,newsz)
+#define STBI_FREE(p)              free(p)
+#endif
+
+#ifndef STBI_REALLOC_SIZED
+#define STBI_REALLOC_SIZED(p,oldsz,newsz) STBI_REALLOC(p,newsz)
 #endif
 
 // x86/x64 detection
@@ -3615,7 +3619,7 @@ static int stbi__zexpand(stbi__zbuf *z, char *zout, int n)  // need to make room
    limit = old_limit = (int) (z->zout_end - z->zout_start);
    while (cur + n > limit)
       limit *= 2;
-   q = (char *) STBI_REALLOC(z->zout_start, old_limit, limit);
+   q = (char *) STBI_REALLOC_SIZED(z->zout_start, old_limit, limit);
    if (q == NULL) return stbi__err("outofmem", "Out of memory");
    z->zout_start = q;
    z->zout       = q + cur;
@@ -4405,7 +4409,7 @@ static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp)
                if (idata_limit == 0) idata_limit = c.length > 4096 ? c.length : 4096;
                while (ioff + c.length > idata_limit)
                   idata_limit *= 2;
-               p = (stbi_uc *) STBI_REALLOC(z->idata, idata_limit_old, idata_limit); if (p == NULL) return stbi__err("outofmem", "Out of memory");
+               p = (stbi_uc *) STBI_REALLOC_SIZED(z->idata, idata_limit_old, idata_limit); if (p == NULL) return stbi__err("outofmem", "Out of memory");
                z->idata = p;
             }
             if (!stbi__getn(s, z->idata+ioff,c.length)) return stbi__err("outofdata","Corrupt PNG");

stb_image_write.h

@@ -157,19 +157,25 @@ STBIWDEF int stbi_write_hdr_to_func(stbi_write_func *func, void *context, int w,
 #include <string.h>
 #include <math.h>
 
-#if defined(STBIW_MALLOC) && defined(STBIW_FREE) && defined(STBIW_REALLOC)
+#if defined(STBIW_MALLOC) && defined(STBIW_FREE) && (defined(STBIW_REALLOC) || defined(STBIW_REALLOC_SIZED))
 // ok
-#elif !defined(STBIW_MALLOC) && !defined(STBIW_FREE) && !defined(STBIW_REALLOC)
+#elif !defined(STBIW_MALLOC) && !defined(STBIW_FREE) && !defined(STBIW_REALLOC) && !defined(STBIW_REALLOC_SIZED)
 // ok
 #else
-#error "Must define all or none of STBIW_MALLOC, STBIW_FREE, and STBIW_REALLOC."
+#error "Must define all or none of STBIW_MALLOC, STBIW_FREE, and STBIW_REALLOC (or STBIW_REALLOC_SIZED)."
 #endif
 
 #ifndef STBIW_MALLOC
-#define STBIW_MALLOC(sz)             malloc(sz)
-#define STBIW_REALLOC(p,oldsz,newsz) realloc(p,newsz)
-#define STBIW_FREE(p)                free(p)
+#define STBIW_MALLOC(sz)        malloc(sz)
+#define STBIW_REALLOC(p,newsz)  realloc(p,newsz)
+#define STBIW_FREE(p)           free(p)
 #endif
+
+#ifndef STBIW_REALLOC_SIZED
+#define STBIW_REALLOC_SIZED(p,oldsz,newsz) STBIW_REALLOC(p,newsz)
+#endif
+
+
 #ifndef STBIW_MEMMOVE
 #define STBIW_MEMMOVE(a,b,sz) memmove(a,b,sz)
 #endif
@@ -647,7 +653,7 @@ int stbi_write_hdr(char const *filename, int x, int y, int comp, const float *da
 static void *stbiw__sbgrowf(void **arr, int increment, int itemsize)
 {
    int m = *arr ? 2*stbiw__sbm(*arr)+increment : increment+1;
-   void *p = STBIW_REALLOC(*arr ? stbiw__sbraw(*arr) : 0, *arr ? (stbiw__sbm(*arr)*itemsize + sizeof(int)*2) : 0, itemsize * m + sizeof(int)*2);
+   void *p = STBIW_REALLOC_SIZED(*arr ? stbiw__sbraw(*arr) : 0, *arr ? (stbiw__sbm(*arr)*itemsize + sizeof(int)*2) : 0, itemsize * m + sizeof(int)*2);
    STBIW_ASSERT(p);
    if (p) {
       if (!*arr) ((int *) p)[1] = 0;