wcsmbs: Use loop_unroll on wcschr

This allows an architecture to set explicit loop unrolling.

Checked on aarch64-linux-gnu.

	* wcsmbs/wcschr.c (WCSCHR): Use loop_unroll.h to parametrize
	the loop unroll.

ChangeLog

@@ -1,5 +1,8 @@
 2019-04-04  Adhemerval Zanella  <[email protected]>
 
+	* wcsmbs/wcschr.c (WCSCHR): Use loop_unroll.h to parametrize
+	the loop unroll.
+
 	* sysdeps/powerpc/Makefile [$(subdir) == wcsmbs] (CFLAGS-wcscpy.c):
 	New rule.
 	* sysdeps/powerpc/power6/wcscpy.c: Remove file.

wcsmbs/wcschr.c

@@ -16,6 +16,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <wchar.h>
+#include <loop_unroll.h>
 
 #ifndef WCSCHR
 # define WCSCHR __wcschr
@@ -25,12 +26,23 @@
 wchar_t *
 WCSCHR (const wchar_t *wcs, const wchar_t wc)
 {
-  do
-    if (*wcs == wc)
-      return (wchar_t *) wcs;
-  while (*wcs++ != L'\0');
+  wchar_t *dest = NULL;
 
-  return NULL;
+#define ITERATION(index)		\
+  ({					\
+    if (*wcs == wc)			\
+      dest = (wchar_t*) wcs;		\
+    dest == NULL && *wcs++ != L'\0';	\
+  })
+
+#ifndef UNROLL_NTIMES
+# define UNROLL_NTIMES 1
+#endif
+
+  while (1)
+    UNROLL_REPEAT (UNROLL_NTIMES, ITERATION);
+
+  return dest;
 }
 libc_hidden_def (__wcschr)
 weak_alias (__wcschr, wcschr)