c++: Fox template-introduction tentative parsing in class bodies clear colon_corrects...

c++: Fox template-introduction tentative parsing in class bodies clear colon_corrects_to_scope_p [PR105061]

The concepts support (in particular template introductions from concepts TS)
broke the following testcase, valid unnamed bitfields with dependent
types (or even just typedefs) were diagnosed as typos (: instead of correct
::) in template introduction during their tentative parsing.
The following patch fixes that by not doing this : to :: correction when
member_p is true.

2022-03-30  Jakub Jelinek  <jakub@redhat.com>

	PR c++/105061
	* parser.c (cp_parser_template_introduction): If member_p, temporarily
	clear parser->colon_corrects_to_scope_p around tentative parsing of
	nested name specifier.

	* g++.dg/concepts/pr105061.C: New test.

(cherry picked from commit 4f2795218a6ba6a7b7b9b18ca7a6e390661e1608)