Klaas de Vries:  Fix bug in libc++'s std::string::find_first_not_of.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@171321 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/string b/include/string
index 5bf42f0..1a70467 100644
--- a/include/string
+++ b/include/string
@@ -3374,7 +3374,7 @@
     {
         const_pointer __p = data();
         const_pointer __pe = __p + __sz;
-        for (const_pointer __ps = __p + __pos; __p != __pe; ++__ps)
+        for (const_pointer __ps = __p + __pos; __ps != __pe; ++__ps)
             if (!traits_type::eq(*__ps, __c))
                 return static_cast<size_type>(__ps - __p);
     }