remote: drop free_refspecs() function

remote: drop free_refspecs() function

We already have free_refspec(), a public function which does
the same thing as the static free_refspecs(). Let's just
keep one.  There are two minor differences between the
functions:

  1. free_refspecs() is a noop when the refspec argument is
     NULL. This probably doesn't matter in practice.  The
     nr_refspec parameter would presumably be 0 in that
     case, skipping the loop. And free(NULL) is explicitly
     OK. But it doesn't hurt for us to port this extra
     safety to free_refspec(), as one of the callers passes
     a funny "i+1" count.

  2. The order of arguments is reversed between the two
     functions. This patch uses the already-public order of
     free_refspec(), as it matches the argument order on the
     parsing side.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>