Fix clang-format binary selection

Also fix spaces to tabs

util/travis/lint.sh

@@ -1,7 +1,11 @@
 #! /bin/bash
 function perform_lint() {
 	echo "Performing LINT..."
+	if hash clang-format-3.9 2>/dev/null; then
+		CLANG_FORMAT=clang-format-3.9
+	else
 		CLANG_FORMAT=clang-format
+	fi
 	CLANG_FORMAT_WHITELIST="util/travis/clang-format-whitelist.txt"
 
 	if [ "$TRAVIS_EVENT_TYPE" = "pull_request" ]; then