vercmptest: fix binary existence check

Signed-off-by: Dan McGee <dan@archlinux.org>

pactest/vercmptest.sh

@@ -62,7 +62,7 @@ runtest() {
 # use first arg as our binary if specified
 [ -n "$1" ] && bin="$1"
 
-if [ ! -x "$bin" ]; then
+if [ ! $(type -p "$bin") ]; then
 	echo "vercmp binary ($bin) could not be located"
 	exit 1
 fi