Declare pthread_atfork as weak to avoid a fatal error with LLVM 13

Fixes behavior with current clang, which marks the symbol as GLOBAL
instead of WEAK.  LLVM change: https://reviews.llvm.org/D90108
base-gcc is unaffected.  Keep asm(".weak") for gcc3 until a cleanup can
be tested there.

Initial diff from mortimer@, input and ok kettenis@, ok guenther@

diff --git a/lib/csu/crtbeginS.c b/lib/csu/crtbeginS.c
index a4a7cd1..cfaf7e4 100644 (file)
--- a/lib/csu/crtbeginS.c
+++ b/lib/csu/crtbeginS.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: crtbeginS.c,v 1.20 2019/01/09 16:42:38 visa Exp $     */
+/*     $OpenBSD: crtbeginS.c,v 1.21 2021/12/17 12:03:16 jca Exp $      */
 /*     $NetBSD: crtbegin.c,v 1.1 1996/09/12 16:59:03 cgd Exp $ */
 
 /*
@@ -83,6 +83,8 @@ asm(".hidden atexit");
  */
 int    _thread_atfork(void (*)(void), void (*)(void), void (*)(void), void *)
            __attribute__((weak));
+int    pthread_atfork(void (*)(void), void (*)(void), void (*)(void))
+           __attribute__((weak));
 
 int
 pthread_atfork(void (*prep)(void), void (*parent)(void), void (*child)(void))