[PATCH] libstdc++-v3: Add -fcf-protection=none to -march=i486

[H.J. Lu via Gcc-patches]

-fcf-protection is automatically enabled in libstdc++ on Linux/x86.
Starting from

commit 77d372abec0fbf2cfe922e3140ee3410248f979e
Author: H.J. Lu <hjl.to...@gmail.com>
Date:   Thu Jan 14 05:56:46 2021 -0800

    x86: Error on -fcf-protection with incompatible target

GCC issues an error on -fcf-protection with incompatible target:

... -fcf-protection ... 
libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc  
-m32   -O2 -g0 -fno-exceptions -fno-asynchronous-unwind-tables -march=i486 ...
cc1plus: error: '-fcf-protection' is not compatible with this target
FAIL: 29_atomics/atomic_flag/test_and_set/explicit-hle.cc (test for excess 
errors)

Add -fcf-protection=none to -march=i486 to compile explicit-hle.cc.

Checked it in as an obvious fix.

        * testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc:
        Add -fcf-protection=none to -march=i486.
---
 .../29_atomics/atomic_flag/test_and_set/explicit-hle.cc         | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git 
a/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc 
b/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc
index 0fd81709688..8ec46283208 100644
--- a/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc
@@ -1,6 +1,6 @@
 // { dg-do compile { target i?86-*-* x86_64-*-* } }
 // { dg-options "-O2 -g0 -fno-exceptions -fno-asynchronous-unwind-tables" }
-// { dg-additional-options "-march=i486" { target ia32 } }
+// { dg-additional-options "-march=i486 -fcf-protection=none" { target ia32 } }
 // { dg-require-effective-target c++11 }
 // { dg-skip-if "scans fail with LTO" { lto } { "-flto" } }
 // { dg-final { scan-assembler-times "xacquire\|\.byte\[^\n\r]*0xf2" 14 } }
-- 
2.29.2