c++: adjust the extra ; warning [PR113760]

A minimal fix to quash an extra ; warning.  I have a more complete
patch for GCC 15.

	DR 1693
	PR c++/113760

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_member_declaration): Only pedwarn about an extra
	semicolon in C++98.

gcc/testsuite/ChangeLog:

	* g++.dg/semicolon-fixits.C: Run in C++98 only.
	* g++.dg/warn/pedantic2.C: Adjust dg-warning.
	* g++.old-deja/g++.jason/parse11.C: Adjust dg-error.
	* g++.dg/DRs/dr1693-1.C: New test.
	* g++.dg/DRs/dr1693-2.C: New test.