indent: search for !=4 spaces indentation

With this change, dib-lint raises an error if when finding an element
using space indentation that is not multiple of 4.

Co-Authored-By: Jon-Paul Sullivan <jonpaul.sullivan@hp.com>

Change-Id: I470e1fdfc38a3f3c7ba5644c5103f2a9ef073005

bin/dib-lint

@@ -45,12 +45,18 @@ trap "rm -rf $TMPDIR" EXIT
 for i in $(find elements -type f); do
     exclusions=("$(parse_exclusions $i)")
     # Check that files starting with a shebang are +x
-    if ! excluded executable; then
     firstline=$(head -n 1 "$i")
-        if [ ! -x "$i" ] && [ "${firstline:0:2}" = "#!" ]; then
+    if [ "${firstline:0:2}" = "#!" ]; then
+        if [ ! -x "$i" ] && ! excluded executable; then
             echo "ERROR: $i is not executable"
             rc=1
         fi
+
+        # Ensure 4 spaces indent are used
+        if grep -q "^ \{4\}* \{1,3\}[^ ]" ${i}; then
+            echo "ERROR: $i should use 4 spaces indent"
+            rc=1
+        fi
     fi
 
     # Check alphabetical ordering of element-deps