thread: change variable name before it become unallowed (vlang#529)

thread.c.v

@@ -108,15 +108,15 @@ pub fn create_thread_with_stack_size(func ThreadFunction, const_name &char, cons
 	return unsafe { nil }
 }
 
-fn C.SDL_GetThreadName(thread &C.SDL_Thread) &char
+fn C.SDL_GetThreadName(pthread &C.SDL_Thread) &char
 
 // get_thread_name gets the thread name, as it was specified in SDL_CreateThread().
 // This function returns a pointer to a UTF-8 string that names the
 // specified thread, or NULL if it doesn't have a name. This is internal
 // memory, not to be free()'d by the caller, and remains valid until the
 // specified thread is cleaned up by SDL_WaitThread().
-pub fn get_thread_name(thread &Thread) &char {
-	return C.SDL_GetThreadName(thread)
+pub fn get_thread_name(pthread &Thread) &char {
+	return C.SDL_GetThreadName(pthread)
 }
 
 fn C.SDL_ThreadID() C.SDL_threadID