Cleanup style nit of 'x == NULL' in remote.c
Cleanup style nit of 'x == NULL' in remote.c

Git style tends to prefer "!x" over "x == NULL".  Make it so in
these handful of locations that were not following along.

Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>
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