zdtm: Allow to specify more than one exclude pattern

We sometimes want to exclude several tests from run. Writing
expression with \-s is annoying. Let's make it possible to
do several -x's instead.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -693,7 +693,11 @@ while :; do
 		;;
 	  -x)
 		shift
-		EXCLUDE_PATTERN=$1
+		if [ -z "$EXCLUDE_PATTERN" ]; then
+			EXCLUDE_PATTERN=$1
+		else
+			EXCLUDE_PATTERN="${EXCLUDE_PATTERN}\|$1"
+		fi
 		shift
 		;;
 	  -t)