* expression.h (parse_expression_for_completion): Rename

	* expression.h (parse_expression_for_completion): Rename
	from parse_field_expression.
	(parse_completion): Rename from in_parse_field.
	* c-exp.y (lex_one_token): Update.
	* completer.c (expression_completer): Update.
	* go-exp.y (lex_one_token): Update.
	* p-exp.y (yylex): Update.
	* parse.c (parse_completion): Rename from in_parse_field.
	(parse_exp_in_context): Update.
	(parse_expression_for_completion): Rename from
	parse_field_expression.  Update.