[PATCH] Do not transform strchr into rawmemchr

[Wilco Dijkstra]

GLIBC uses strchr (s, '\0') as an idiom to find the end of a string.
This is transformed into rawmemchr by the bits/string2.h header.
However this is generally slower than strlen on most targets, even when
an optimized rawmemchr implementation exists.  Since GCC7 optimizes
strchr (s, '\0') to strlen (s) + s, the GLIBC headers should not
transform this to rawmemchr.

GLIBC tests pass, OK for commit?

ChangeLog:
2015-11-16  Wilco Dijkstra  <wdijkstr@arm.com>

        * string/bits/string2.h (strchr): Use __builtin_strchr.
--
diff --git a/string/bits/string2.h b/string/bits/string2.h
index 80987602f34ded483854bcea86dabd5b81e42a18..f0e2ce9cd87033698236e7878c63a2e5f9bb1887 100644
--- a/string/bits/string2.h
+++ b/string/bits/string2.h
@@ -59,12 +59,7 @@
 
 
 #ifndef _HAVE_STRING_ARCH_strchr
-extern void *__rawmemchr (const void *__s, int __c);
-#  define strchr(s, c) \
-  (__extension__ (__builtin_constant_p (c) && !__builtin_constant_p (s)              \
-                 && (c) == '\0'                                       \
-                 ? (char *) __rawmemchr (s, c)                                \
-                 : __builtin_strchr (s, c)))
+# define strchr(s, c) __builtin_strchr (s, c)
 #endif