cvsimport: always pass user data to "system" as a list
cvsimport: always pass user data to "system" as a list

This avoids invoking the shell. Not only is it faster, but
it prevents the possibility of interpreting our arguments in
the shell.

Signed-off-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