jenkins.sh: simpler invocation of verify_value_string_...

The script
osmo-ci/scripts/verify_value_string_arrays_are_terminated.py
is able to find .c/.h files in directory trees by itself.

Shorten the cmdline invocation of this script for libosmocore.

Change-Id: I888c20b9b19d777cd6581a541536842292f434b9
diff --git a/contrib/jenkins_common.sh b/contrib/jenkins_common.sh
index fa1d544..b86a479 100644
--- a/contrib/jenkins_common.sh
+++ b/contrib/jenkins_common.sh
@@ -10,7 +10,7 @@
 
 osmo-clean-workspace.sh
 
-verify_value_string_arrays_are_terminated.py $(find . -name "*.[hc]")
+verify_value_string_arrays_are_terminated.py
 
 prep_build() {
     _src_dir="$1"