[PATCH v4 1/2] x86: Add missing IS_IN (libc) check to strncmp-sse4_2.S

[Noah Goldstein]

Was missing to for the multiarch build rtld-strncmp-sse4_2.os was
being built and exporting symbols:

build/glibc/string/rtld-strncmp-sse4_2.os:
0000000000000000 T __strncmp_sse42

Introduced in:

commit 11ffcacb64a939c10cfc713746b8ec88837f5c4a
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Jun 21 12:10:50 2017 -0700

    x86-64: Implement strcmp family IFUNC selectors in C
---
 sysdeps/x86_64/multiarch/strncmp-sse4_2.S | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/sysdeps/x86_64/multiarch/strncmp-sse4_2.S b/sysdeps/x86_64/multiarch/strncmp-sse4_2.S
index 9773e5fc09..310a6dbe77 100644
--- a/sysdeps/x86_64/multiarch/strncmp-sse4_2.S
+++ b/sysdeps/x86_64/multiarch/strncmp-sse4_2.S
@@ -16,6 +16,8 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#define STRCMP_SSE42 __strncmp_sse42
-#define USE_AS_STRNCMP
-#include "strcmp-sse42.S"
+#if IS_IN (libc)
+# define STRCMP_SSE42 __strncmp_sse42
+# define USE_AS_STRNCMP
+# include "strcmp-sse42.S"
+#endif
-- 
2.34.1