format-code: handle all files are ignored by linter

If all the files applicable to a linter have been ignored, then
we should not call the linter since many executables fail if no
source files are given as arguments.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I014291d807b2ef6be7ec3c5a5d3e7a4ce1de3717
diff --git a/scripts/format-code.sh b/scripts/format-code.sh
index bd7cb10..c7bf16c 100755
--- a/scripts/format-code.sh
+++ b/scripts/format-code.sh
@@ -306,9 +306,13 @@
     done | "${LOCAL_IGNORE[@]}")
 
     # Call the linter now with all the files.
-    echo -e "    ${BLUE}Running $op${NORMAL}"
-    if ! "do_$op" "${LINTER_FILES[@]}" ; then
-        LINTERS_FAILED+=([$op]=1)
+    if [ 0 -ne ${#LINTER_FILES[@]} ]; then
+        echo -e "    ${BLUE}Running $op${NORMAL}"
+        if ! "do_$op" "${LINTER_FILES[@]}" ; then
+            LINTERS_FAILED+=([$op]=1)
+        fi
+    else
+        echo -e "    ${YELLOW}${op}:${NORMAL} all applicable files are on ignore-lists"
     fi
 done