c++: Further -fcontract* option description fixes

c++: Further -fcontract* option description fixes

During testing I've missed my previous patch just changed:
-FAIL: compiler driver --help=c++ option(s): "^ +-.*[^:.]\$" absent from output: "  -fcontract-build-level=[off|default|audit] Specify max contract level to generate runtime checks for"
+FAIL: compiler driver --help=c++ option(s): "^ +-.*[^:.]\$" absent from output: "  -fcontract-role=<name>:<semantics> Specify the semantics for all levels in a role (default, review), or a custom contract role with given semantics (ex: opt:assume,assume,assume)"
rather than actually fixed it, the test only reports the first such problem.

This patch fixes the remaining ones.

2022-11-24  Jakub Jelinek  <jakub@redhat.com>

	* c.opt (fcontract-role=, fcontract-semantic=): Terminate descriptions
	with a dot.