Use the helper macro MOVE_ARRAY to move arrays.  This is shorter and
safer, as it automatically infers the size of elements.

Patch generated by Coccinelle and contrib/coccinelle/array.cocci in
Travis CI's static analysis build job.
Signed-off-by: NSZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>