x86: Add missing IS_IN (libc) check to strcspn-sse4.c

Was missing to for the multiarch build rtld-strcspn-sse4.os was
being built and exporting symbols:

build/glibc/string/rtld-strcspn-sse4.os:
                 U ___m128i_shift_right
                 U __strcspn_generic
0000000000000000 T __strcspn_sse42
                 U strlen

build/glibc/string/rtld-varshift.os:
0000000000000000 R ___m128i_shift_right

Introduced in:

commit 06e51c8f3d
Author: H.J. Lu <hongjiu.lu@intel.com>
Date:   Fri Jul 3 02:48:56 2009 -0700

    Add SSE4.2 support for strcspn, strpbrk, and strspn on x86-64.

sysdeps/x86_64/multiarch/strcspn-sse4.c

@@ -16,9 +16,11 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <nmmintrin.h>
-#include <string.h>
-#include "varshift.h"
+#if IS_IN (libc)
+
+# include <nmmintrin.h>
+# include <string.h>
+# include "varshift.h"
 
 /* We use 0x2:
 	_SIDD_SBYTE_OPS
@@ -52,31 +54,31 @@
    when either CFlag or ZFlag is 1.  If CFlag == 1, ECX has the offset
    X for case 1.  */
 
-#ifndef STRCSPN_GENERIC
-# define STRCSPN_GENERIC __strcspn_generic
-# define STRCSPN_SSE42 __strcspn_sse42
-#endif
+# ifndef STRCSPN_GENERIC
+#  define STRCSPN_GENERIC __strcspn_generic
+#  define STRCSPN_SSE42 __strcspn_sse42
+# endif
 
-#ifdef USE_AS_STRPBRK
-# define RETURN(val1, val2) return val1
-#else
-# define RETURN(val1, val2) return val2
-#endif
+# ifdef USE_AS_STRPBRK
+#  define RETURN(val1, val2) return val1
+# else
+#  define RETURN(val1, val2) return val2
+# endif
 
 extern
-#ifdef USE_AS_STRPBRK
+# ifdef USE_AS_STRPBRK
 char *
-#else
+# else
 size_t
-#endif
+# endif
 STRCSPN_GENERIC (const char *, const char *) attribute_hidden;
 
 
-#ifdef USE_AS_STRPBRK
+# ifdef USE_AS_STRPBRK
 char *
-#else
+# else
 size_t
-#endif
+# endif
 __attribute__ ((section (".text.sse4.2")))
 STRCSPN_SSE42 (const char *s, const char *a)
 {
@@ -161,3 +163,4 @@ start_loop:
       aligned += 16;
     }
 }
+#endif

sysdeps/x86_64/multiarch/varshift.c

@@ -16,7 +16,8 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <stdint.h>
+#if IS_IN (libc)
+# include <stdint.h>
 
 const int8_t ___m128i_shift_right[31] attribute_hidden
     __attribute__((aligned(32))) =
@@ -24,3 +25,5 @@ const int8_t ___m128i_shift_right[31] attribute_hidden
     0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
   };
+
+#endif