jenkins: print gcc version in log

Change-Id: I8dfac78868f64213413e80cc52ac585d9d4a2c93
diff --git a/contrib/jenkins_arch.sh b/contrib/jenkins_arch.sh
index 99ce5c1..93dd8bb 100755
--- a/contrib/jenkins_arch.sh
+++ b/contrib/jenkins_arch.sh
@@ -14,7 +14,11 @@
   exit 1
 fi
 
-set -x -e
+set -x
+
+gcc --version
+
+set -e
 
 case "$arch" in