mallocng: prevent stray ';' at top-level

The LOCK_OBJ_DEF macro is used with a trailing semicolon. However,
since the macro definition ends with the closing brace of a function
definition, the ISO C grammar does not allow an extra semicolon.

To fix this, swap the order of the two definitions, and drop the
semicolon from the __malloc_lock declaration.

src/malloc/mallocng/glue.h

@@ -62,8 +62,8 @@ __attribute__((__visibility__("hidden")))
 extern int __malloc_lock[1];
 
 #define LOCK_OBJ_DEF \
-int __malloc_lock[1]; \
-void __malloc_atfork(int who) { malloc_atfork(who); }
+void __malloc_atfork(int who) { malloc_atfork(who); } \
+int __malloc_lock[1]
 
 static inline void rdlock()
 {