libgcompat: Add and use a macro for defining symbol aliases

* Prefer providing the underscore-prefixed symbol as the strong
  definition.
* Do not use a weak alias if the alias is also underscore-prefixed.
* Make libgcompat objects depend on the new header.

[NOTE: I originally took the weak_alias macro from musl's libc.h, but
       it's trivial and the same pattern already in use. If desired, I
       can add the musl copyright notice.]

Signed-off-by: Samuel Holland <samuel@sholland.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/libgcompat/pthread.c b/libgcompat/pthread.c
index 52daceb..9333554 100644
--- a/libgcompat/pthread.c
+++ b/libgcompat/pthread.c
@@ -1,14 +1,13 @@
 #include <pthread.h>
 
+#include "alias.h" /* weak_alias */
+
 int __register_atfork(void (*prepare)(void), void (*parent)(void),
                       void (*child)(void))
 {
 	return pthread_atfork(prepare, parent, child);
 }
-
-int register_atfork(void (*prepare)(void), void (*parent)(void),
-                    void (*child)(void))
-    __attribute__((weak, alias("__register_atfork")));
+weak_alias(__register_atfork, register_atfork);
 
 void __pthread_register_cancel(void *buf)
 {