tools: add a script for fixing up TABs

This is similar to "find-double-newline.sh" but looks for TABs that
should not be there.

tools/find-tabs.sh

@@ -0,0 +1,40 @@
+#!/bin/sh
+# SPDX-License-Identifier: LGPL-2.1+
+
+case "$1" in
+
+        recdiff)
+                if [ "$2" = "" ] ; then
+                        DIR="$PWD/.."
+                else
+                        DIR="$2"
+                fi
+
+                find $DIR -type f \( -name '*.[ch]' -o -name '*.xml' \) -exec $0 diff \{\} \;
+                ;;
+
+        recpatch)
+                if [ "$2" = "" ] ; then
+                        DIR="$PWD/.."
+                else
+                        DIR="$2"
+                fi
+
+                find $DIR -type f \( -name '*.[ch]' -o -name '*.xml' \) -exec $0 patch \{\} \;
+                ;;
+
+        diff)
+                T=`mktemp`
+                sed 's/\t/        /g' < "$2" > "$T"
+                diff -u "$2" "$T"
+                rm -f "$T"
+                ;;
+
+        patch)
+                sed -i 's/\t/        /g' "$2"
+                ;;
+
+        *)
+                echo "Expected recdiff|recpatch|diff|patch as verb." >&2
+                ;;
+esac