Removed redundant requirement for std::regex::multiline (Fixes #191)

tests/catch.h

@@ -13301,9 +13301,6 @@ bool RegexMatcher::match(std::string const &matchee) const
 {
     auto flags = std::regex::ECMAScript; // ECMAScript is the default syntax
                                          // option anyway
-#if !defined(_WIN32)
-    flags |= std::regex::multiline;
-#endif
 
     if (m_caseSensitivity == CaseSensitive::Choice::No) {
         flags |= std::regex::icase;