Port custom allocators (WINGs memory.c) to Rust.

This introduces the crate wutil-rs, which is intended to be the destination for
migrating the API of WINGs/WINGs/WUtil.h to Rust.

src/main.c

@@ -624,7 +624,6 @@ static int real_main(int argc, char **argv)
 	int d, s;
 
 	setlocale(LC_ALL, "");
-	wsetabort(wAbort);
 
 	/* for telling WPrefs what's the name of the wmaker binary being ran */
 	setenv("WMAKER_BIN_NAME", argv[0], 1);