diffcore-pickaxe: simplify has_changes and contains
diffcore-pickaxe: simplify has_changes and contains

Halve the number of callsites of contains() to two using temporary
variables, simplifying the code.  While at it, get rid of the
diff_options parameter, which became unused with 8fa4b09f.

Signed-off-by: René Scharfe <5c721353370dda279bee7751cb8d3ff68ef77242@lsrfire.ath.cx>
Acked-by: Jeff King <696e3fbcf235d40b6ea1ebd61c87cbea79d444e7@peff.net>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git