Move comma_terminates global to parser_state

Move comma_terminates global to parser_state

This moves the comma_terminates global to parser_state.

gdb/ChangeLog
2019-04-04  Tom Tromey  <tom@tromey.com>

	* rust-exp.y (rustyylex, rust_lex_tests): Update.
	* parser-defs.h (struct parser_state) <parser_state>: Add new
	parameter.
	<comma_terminates>: New member.
	(comma_terminates): Don't declare global.
	* parse.c (comma_terminates): Remove global.
	(parse_exp_in_context): Update.
	* p-exp.y (yylex): Update.
	* m2-exp.y (yylex): Update.
	* go-exp.y (lex_one_token): Update.
	* f-exp.y (yylex): Update.
	* d-exp.y (lex_one_token): Update.
	* c-exp.y (lex_one_token): Update.
	* ada-lex.l: Update.