[vala] tests: Do not use xargs GNU extension in the test runner

[Jürg Billeter <juergbi src gnome org>]

commit d5a49d474214cc082d22e68736e12a492b1b7bbf
Author: Alexander Kojevnikov <alexander kojevnikov com>
Date:   Wed Mar 16 14:41:10 2011 +0800

    tests: Do not use xargs GNU extension in the test runner
    
    Fixes bug 644884.

 tests/testrunner.sh |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/tests/testrunner.sh b/tests/testrunner.sh
index ee5ec01..0d477ea 100755
--- a/tests/testrunner.sh
+++ b/tests/testrunner.sh
@@ -164,7 +164,7 @@ EOF
 
 cat $SOURCEFILES >> main.vala
 
-if $VALAC $VALAFLAGS -o test$EXEEXT $(echo $PACKAGES | xargs -n 1 -r echo -n " --pkg") main.vala &>log; then
+if $VALAC $VALAFLAGS -o test$EXEEXT $([ -z "$PACKAGES" ] || echo $PACKAGES | xargs -n 1 echo -n " --pkg") main.vala &>log; then
 	echo -e "\033[0;32mOK\033[m"
 else
 	echo -e "\033[0;31mFAIL\033[m"