os: remove INTERNAL_MALLOC define.

There doesn't seem to be anything that defines it and given that the
counterpart (the X internal malloc) was removed in
01cfba7522 it's unlikely to work anyway.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

os/utils.c

@@ -1032,8 +1032,6 @@ set_font_authorizations(char **authorizations, int *authlen, pointer client)
 #endif /* TCPCONN */
 }
 
-#ifndef INTERNAL_MALLOC
-
 void *
 Xalloc(unsigned long amount)
 {
@@ -1149,7 +1147,6 @@ Xfree(pointer ptr)
     if (ptr)
 	free(ptr); 
 }
-#endif /* !INTERNAL_MALLOC */
 
 
 char *