Implement P0253R1: Fixing a design mistake in the searchers interface.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@262928 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/string b/include/string
index 9150244..004dc3d 100644
--- a/include/string
+++ b/include/string
@@ -982,7 +982,7 @@
     const _CharT* __r = 
         _VSTD::__search(__p + __pos, __p + __sz,
                         __s, __s + __n, _Traits::eq,
-                        random_access_iterator_tag(), random_access_iterator_tag());
+                        random_access_iterator_tag(), random_access_iterator_tag()).first;
     if (__r == __p + __sz)
         return __npos;
     return static_cast<_SizeT>(__r - __p);