Fix undefined behavior in syntax_option_type::operator~ and match_flag_type::operator./a.out  Found by UBSan

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@177693 91177308-0d34-0410-b5e6-96231b3b80d8
Fix buffer read overflow in money_get::do_get(). Found by UBSan

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@177694 91177308-0d34-0410-b5e6-96231b3b80d8