[gcc r13-4482] libstdc++, Darwin: Limit recursive mutex init to OS versions needing it.

[Iain D Sandoe]

https://gcc.gnu.org/g:a044c9d25972b22c6b4c8ec27f2de5fd622573cc

commit r13-4482-ga044c9d25972b22c6b4c8ec27f2de5fd622573cc
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Sat Dec 3 17:09:35 2022 +0000

    libstdc++, Darwin: Limit recursive mutex init to OS versions needing it.
    
    The problem described in pr 51906 was fixed in the next OS release.  Limit the
    workaround to systems that need it.
    
    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
    
    libstdc++-v3/ChangeLog:
    
            * config/os/bsd/darwin/os_defines.h
            (_GTHREAD_USE_RECURSIVE_MUTEX_INIT_FUNC): Limit use of this macro
            to OS versions that need it.

Diff:
---
 libstdc++-v3/config/os/bsd/darwin/os_defines.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/config/os/bsd/darwin/os_defines.h b/libstdc++-v3/config/os/bsd/darwin/os_defines.h
index 38fdfb5f6f0..5b611d32e0d 100644
--- a/libstdc++-v3/config/os/bsd/darwin/os_defines.h
+++ b/libstdc++-v3/config/os/bsd/darwin/os_defines.h
@@ -39,8 +39,12 @@
 // implementation is not itself a weak definition).
 #define _GLIBCXX_WEAK_DEFINITION __attribute__ ((__weak__))
 
-// Static initializer macro is buggy in darwin, see libstdc++/51906
+#if defined (__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) \
+     && (__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 1080)
+// Static initializer macro is absent for Darwin < 11 and buggy in Darwin 11,
+// see libstdc++/51906.  Fixed in Darwin 12 (OS X 10.8).
 #define _GTHREAD_USE_RECURSIVE_MUTEX_INIT_FUNC
+#endif
 
 // Configure checks for nanosleep fail on Darwin, but nanosleep and
 // sched_yield are always available, so use them.