Clean up some bare malloc/free calls.

These should use the same macros as the rest of the code.

src/stream.c

@@ -141,7 +141,7 @@ static wchar_t *op_utf8_to_utf16(const char *_src){
   size_t   len;
   len=strlen(_src);
   /*Worst-case output is 1 wide character per 1 input character.*/
-  dst=(wchar_t *)malloc(sizeof(*dst)*(len+1));
+  dst=(wchar_t *)_ogg_malloc(sizeof(*dst)*(len+1));
   if(dst!=NULL){
     size_t si;
     size_t di;
@@ -218,7 +218,7 @@ static wchar_t *op_utf8_to_utf16(const char *_src){
         }
       }
       /*If we got here, we encountered an illegal UTF-8 sequence.*/
-      free(dst);
+      _ogg_free(dst);
       return NULL;
     }
     OP_ASSERT(di<=len);
@@ -244,8 +244,8 @@ void *op_fopen(OpusFileCallbacks *_cb,const char *_path,const char *_mode){
     if(wmode==NULL)errno=EINVAL;
     else if(wpath==NULL)errno=ENOENT;
     else fp=_wfopen(wpath,wmode);
-    free(wmode);
-    free(wpath);
+    _ogg_free(wmode);
+    _ogg_free(wpath);
   }
 #endif
   if(fp!=NULL)*_cb=*&OP_FILE_CALLBACKS;
@@ -275,8 +275,8 @@ void *op_freopen(OpusFileCallbacks *_cb,const char *_path,const char *_mode,
     if(wmode==NULL)errno=EINVAL;
     else if(wpath==NULL)errno=ENOENT;
     else fp=_wfreopen(wpath,wmode,(FILE *)_stream);
-    free(wmode);
-    free(wpath);
+    _ogg_free(wmode);
+    _ogg_free(wpath);
   }
 #endif
   if(fp!=NULL)*_cb=*&OP_FILE_CALLBACKS;