IVGCVSW-2115: Fix for unset USERNAME

* When running the script standalone USERNAME can be unset causing failure

Change-Id: Idb1752117c319c8946426efe8882f03034b2bbbf
diff --git a/scripts/get_compute_library.sh b/scripts/get_compute_library.sh
index 8d6fb2a..6385011 100755
--- a/scripts/get_compute_library.sh
+++ b/scripts/get_compute_library.sh
@@ -46,6 +46,9 @@
 DIR="$( cd -P "$( dirname "$SRC" )" >/dev/null && pwd )"
 pushd ${DIR} > /dev/null
 cd ../..
+if [ -z "$USERNAME" ]; then
+    USERNAME=$USER
+fi
 if [ -z "$GITHUB_USERNAME" ]; then
     GITHUB_USERNAME=$USERNAME
     echo "setting GITHUB_USERNAME: ${GITHUB_USERNAME} use -g command line option to change"