Introduce ScalarTraits::mustQuote which determines whether or not a
StringRef needs quoting before it is acceptable to output.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205955 91177308-0d34-0410-b5e6-96231b3b80d8
YAMLIO would turn a BinaryRef into the string 0000000004000000.
However, the leading zero causes parsers to interpret it as being an
octal number instead of a hexadecimal one.
Instead, escape such strings as needed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205839 91177308-0d34-0410-b5e6-96231b3b80d8
