c++: Fix null deref at EOF [PR96258]

c++: Fix null deref at EOF [PR96258]

cp_parser_declaration peeks at 1 or 2 tokens, when I changed it not to
peek past EOF, I set the second token to NULL.  But there are paths
through the function that just look at the second token.  Fixed by
setting that token to EOF rather than NULL in this case.

	PR c++/96258
	gcc/cp/
	* parser.c (cp_parser_declaration): Make token2 point to EOF if
	token1 was EOF.
	gcc/testsuite/
	* g++.dg/parse/pr96258.C: New.