Bill Fisher:  Fix for failing to throw an exception in regex when parsing an invalid escape sequence.  This fixes http://llvm.org/bugs/show_bug.cgi?id=16023

llvm-svn: 185192
diff --git a/libcxx/include/regex b/libcxx/include/regex
index d1afa54..27c7ecf 100644
--- a/libcxx/include/regex
+++ b/libcxx/include/regex
@@ -4481,7 +4481,7 @@
                 ++__first;
             }
 #ifndef _LIBCPP_NO_EXCEPTIONS
-            else if (__str)
+            else
                 throw regex_error(regex_constants::error_escape);
 #endif  // _LIBCPP_NO_EXCEPTIONS
             break;