Fix ARI warnings in d-exp.y

Fix ARI warnings in d-exp.y

This fixes four ARI warnings found in d-exp.y.

This is comprised of three uses of the && or || at the end of a line, and one
use of sprintf.

gdb/ChangeLog

	* d-exp.y (PrimaryExpression : TypeExp '.' IdentifierExp): Use
	xstrprintf instead of malloc and sprintf.
	(PrimaryExpression : IdentifierExp): Avoid operator at end of line.
	(lex_one_token): Likewise.