Allow wrappers to be missing; quote directory name from make

Co-authored-by: Gilles Peskine <gilles.peskine@arm.com>
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/tests/scripts/quiet/make b/tests/scripts/quiet/make
index a1ef3e5..162d44d 100755
--- a/tests/scripts/quiet/make
+++ b/tests/scripts/quiet/make
@@ -15,4 +15,4 @@
 
 export TOOL="make"
 
-exec $(dirname "$0")/quiet "$@"
+exec "$(dirname "$0")/quiet" "$@"