remove useless if-before-free tests

remove useless if-before-free tests

In case you're wondering about whether this change is safe from a
portability standpoint, fear not.  This has been beaten to death
in other forums.  Here are a few threads:

  http://thread.gmane.org/gmane.comp.version-control.git/74187
  http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/12712
  http://thread.gmane.org/gmane.emacs.devel/98144
  http://thread.gmane.org/gmane.comp.lib.glibc.alpha/13092

There has been debate about whether it's a good idea from a
performance standpoint, too, but imho you'll have a hard time
finding an instance where this sort of change induces a
measurable performance penalty.  If you do, please let me know.

Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>