c: Fix handling of [[gnu::musttail] return in if and else bodies [PR119311]

c: Fix handling of [[gnu::musttail] return in if and else bodies [PR119311]

The following new testcase FAILs with C (and succeeds with C++).
c_parser_handle_musttail is used in c_parser_compound_statement_nostart
where it is directly passed to c_parser_statement_after_labels, and in
c_parser_all_labels where it is returned.  Now, out of the 3
c_parser_all_labels callers, c_parser_statement passes it down to
c_parser_statement_after_labels, but c_parser_if_body and c_parser_else_body
don't, so if there are return statements with [[gnu::musttail]] or
[[clang::musttail]] directly in if or else bodies rather than wrapped with
{}s, we throw that information away.

2025-03-18  Jakub Jelinek  <jakub@redhat.com>

	PR c/119311
	* c-parser.cc (c_parser_if_body): Pass result of c_parser_all_labels
	as last argument to c_parser_statement_after_labels.
	(c_parser_else_body): Likewise.

	* c-c++-common/musttail14.c: Use * instead of \* in the regexps.
	* c-c++-common/musttail25.c: New test.