Prevent some heap corruptions/exceptions

libretro-common/compat/fopen_utf8.c

@@ -22,6 +22,7 @@ FILE* fopen_utf8(const char * filename, const char * mode)
    if (!filename_local)
       return NULL;
    ret = fopen(filename_local, mode);
+   if (filename_local)
       free(filename_local);
    return ret;
 #else

libretro-common/formats/png/rpng.c

@@ -1220,7 +1220,7 @@ bool rpng_set_buf_ptr(rpng_t *rpng, void *data)
 
 rpng_t *rpng_alloc(void)
 {
-   rpng_t *rpng = (rpng_t*)calloc(1, sizeof(rpng_t));
+   rpng_t *rpng = (rpng_t*)calloc(1, sizeof(*rpng));
    if (!rpng)
       return NULL;
    return rpng;

libretro-common/streams/trans_stream_zlib.c

@@ -69,6 +69,7 @@ static void zlib_inflate_stream_free(void *data)
       return;
    if (z->inited)
       inflateEnd(&z->z);
+   if (z)
       free(z);
 }
 

menu/drivers/xmb.c

@@ -3893,6 +3893,7 @@ static void xmb_context_reset(void *data, bool is_threaded)
          xmb_update_thumbnail_image(xmb);
       xmb_update_savestate_thumbnail_image(xmb);
 
+      if (iconpath)
          free(iconpath);
    }
 }