Add non-wrapping mode to ada_decode

Add non-wrapping mode to ada_decode

When ada_decode encounters a name that it cannot decode, it simply
wraps it in <...>, which is used elsewhere in the Ada code to indicate
that a verbatim match should be done.

A subequent patch needed the ability to suppress this wrapping, so
this patch adds a new mode to ada_decode.

2021-06-25  Tom Tromey  <tromey@adacore.com>

	* ada-lang.c (ada_decode): Add wrap parameter.
	* ada-lang.h (ada_decode): Add wrap parameter.