[PATCH v2] libpthread: modify CFLAGS-pthread_once.c to avoid earlier setting being replaced

[Yang Yingliang]

From: Yang Yingliang <yangyingliang at huawei.com>

I use uclibc in arch arm. The CFLAGS-pthread_once.c has been set
to -DNOT_IN_libc -DIS_IN_libpthread in
libpthread/nptl/sysdeps/unix/sysv/linux/arm/Makefile.arch.
But it will be replaced by -fexceptions -fasynchronous-unwind-tables in
libpthread/nptl/Makefile.in.

If CFLAGS-pthread_once.c has no -DIS_IN_libpthread the testcase
tst-once3 in test/nptl/ will be failed. The reason is pthread_once
calls another pthread_cleanup_push() which is not under IS_IN_libpthread
so that clear_once_control do not be called when the thread is canceled.
So pthread_once will hang up when it's called second time.

Other parts don't have this problem, because IS_IN_libpthread is defined by
CFLAGS-nptl = -DNOT_IN_libc -DIS_IN_libpthread $(SSP_ALL_CFLAGS),
CFLAGS-pthread = $(SSP_ALL_CFLAGS) -DNOT_IN_libc -DIS_IN_libpthread,
CFLAGS-dir_linuxthreads := -DNOT_IN_libc -DIS_IN_libpthread and
CFLAGS-dir_linuxthreads.old := -DNOT_IN_libc -DIS_IN_libpthread.

Cc: Waldemar Brodkorb <wbx at openadk.org>
Cc: Bernhard Reutner-Fischer <rep.dot.nop at gmail.com>
Tested-by: Waldemar Brodkorb <wbx at openadk.org>
Signed-off-by: Yang Yingliang <yangyingliang at huawei.com>

---
Change note: 
  Update changelog to describe other parts' IS_IN_libpthread.
  Add Tested-by: Waldemar Brodkorb <wbx at openadk.org>.
---
 libpthread/nptl/Makefile.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libpthread/nptl/Makefile.in b/libpthread/nptl/Makefile.in
index 0008822..1b9ba8c 100644
--- a/libpthread/nptl/Makefile.in
+++ b/libpthread/nptl/Makefile.in
@@ -186,7 +186,7 @@ CFLAGS-forward.c = -fexceptions
 CFLAGS-pthread_testcancel.c = -fexceptions
 CFLAGS-pthread_join.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-pthread_timedjoin.c = -fexceptions -fasynchronous-unwind-tables
-CFLAGS-pthread_once.c = $(uses-callbacks) -fexceptions \
+CFLAGS-pthread_once.c += $(uses-callbacks) -fexceptions \
 			-fasynchronous-unwind-tables
 CFLAGS-pthread_cond_wait.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-pthread_cond_timedwait.c = -fexceptions -fasynchronous-unwind-tables
-- 1.8.0 .