check_bindir: avoid "test <cond> -a/-o <cond>"

The construct is error-prone; "test" being built-in in most modern
shells, the reason to avoid "test <cond> && test <cond>" spawning
one extra process by using a single "test <cond> -a <cond>" no
longer exists.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

check_bindir

@@ -2,7 +2,7 @@
 bindir="$1"
 gitexecdir="$2"
 gitcmd="$3"
-if test "$bindir" != "$gitexecdir" -a -x "$gitcmd"
+if test "$bindir" != "$gitexecdir" && test -x "$gitcmd"
 then
 	echo
 	echo "!! You have installed git-* commands to new gitexecdir."