The scanbuild analysis cannot see that decodeUnicodeEscapeSequence
either initializes the `unicode` argument or returns `false` such
that the code following it runs only if `unicode` is initialized.
Add an explicit initialization to pacify it.
When parsing digits we know our `c - '0'` expression results in a
non-negative value due to preceding conditions. Simply cast the result
to UInt. This fixes compilation on SolarisStudio 12.4.
Brad King
Marc Chevrier