[glib] gthread: Fix a typo in an #ifdef on the non-native mutex path

[Philip Withnall <pwithnall src gnome org>]

commit 79d9ea2598c1385104b4c88843d5d92b0203c498
Author: Philip Withnall <withnall endlessm com>
Date:   Wed Jan 31 22:47:49 2018 +0000

    gthread: Fix a typo in an #ifdef on the non-native mutex path
    
    This seems to have been present since the code was introduced in commit
    cedc82290f860683d695d0c5326db153893eec21. The attr variable is defined
    under one #ifdef, but destroyed under another, which doesn’t make any
    sense. The second #ifdef variable is actually an enum value, rather than
    the static initialiser value which makes more sense in the context.
    
    Note that GMutex used to be statically initialised to the value of
    PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP in gthread.h, before this was
    reworked in commit e081eadda598bc708fbf9dd53a190fc3b0e7fa76.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    https://bugzilla.gnome.org/show_bug.cgi?id=793026

 glib/gthread-posix.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/glib/gthread-posix.c b/glib/gthread-posix.c
index 364c9eb..5fff514 100644
--- a/glib/gthread-posix.c
+++ b/glib/gthread-posix.c
@@ -105,7 +105,7 @@ g_mutex_impl_new (void)
   if G_UNLIKELY ((status = pthread_mutex_init (mutex, pattr)) != 0)
     g_thread_abort (status, "pthread_mutex_init");
 
-#ifdef PTHREAD_ADAPTIVE_MUTEX_NP
+#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
   pthread_mutexattr_destroy (&attr);
 #endif