log: Make the message buffer static.

Now we don't have to worry about allocation failure, or performance
issues or changes to the allocation layout when trying to track down
subtle bugs.

src/SDL_log.c

@@ -284,7 +284,7 @@ GetCategoryPrefix(int category)
 void
 SDL_LogMessageV(int category, SDL_LogPriority priority, const char *fmt, va_list ap)
 {
-    char *message;
+    static char message[SDL_MAX_LOG_MESSAGE]
     size_t len;
 
     /* Nothing to do if we don't have an output function */
@@ -302,9 +302,13 @@ SDL_LogMessageV(int category, SDL_LogPriority priority, const char *fmt, va_list
         return;
     }
 
-    message = (char *) SDL_malloc(SDL_MAX_LOG_MESSAGE);
-    if (!message) {
-        return;
+    if (!log_function_mutex) {
+        /* this mutex creation can race if you log from two threads at startup. You should have called SDL_Init first! */
+        log_function_mutex = SDL_CreateMutex();
+    }
+
+    if (log_function_mutex) {
+        SDL_LockMutex(log_function_mutex);
     }
 
     SDL_vsnprintf(message, SDL_MAX_LOG_MESSAGE, fmt, ap);
@@ -318,11 +322,11 @@ SDL_LogMessageV(int category, SDL_LogPriority priority, const char *fmt, va_list
         }
     }
 
-    /* this mutex creation can race if you log from two threads at startup. You should have called SDL_Init first! */
-    if (!log_function_mutex) { log_function_mutex = SDL_CreateMutex(); }
-    if (log_function_mutex) { SDL_LockMutex(log_function_mutex); }
     SDL_log_function(SDL_log_userdata, category, priority, message);
-    if (log_function_mutex) { SDL_UnlockMutex(log_function_mutex); }
+
+    if (log_function_mutex) {
+        SDL_UnlockMutex(log_function_mutex);
+    }
 
     SDL_free(message);
 }