runalltests.sh: remove dirs only if they exist

Author: chfast

scripts/runalltests.sh

@@ -3,8 +3,8 @@
 workdir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 #Clean the previous build
 cd $workdir
-rm -r cpp-ethereum
-rm -r tests
+rm -r cpp-ethereum 2>/dev/null || true
+rm -r tests 2>/dev/null || true
 exec &> $workdir/buildlog.txt
 ETHEREUM_TEST_PATH=$workdir/tests