added TAB checker script, to be added to the PR checker action

.github/checks/Makefile

@@ -0,0 +1,7 @@
+
+.PHONY: tabs
+
+check: tabs
+
+tabs: tabs.sh
+	@./tabs.sh

.github/checks/tabs.sh

@@ -0,0 +1,16 @@
+#! /bin/bash
+OLDCWD=`pwd`
+SCRIPT_PATH=`dirname $0`
+cd $SCRIPT_PATH/../../
+
+FILES=`find $CHECK_PATH -type f \( \( -name \*.inc -a \! -name Makefile.inc \) -o -name \*.cfg -o -name \*.c -o -name \*.s -o -name \*.h -o -name \*.asm -o -name \*.sgml \) -print | xargs grep -l $'\t' | grep -v "libwrk/" | grep -v "testwrk/"`
+
+cd $OLDCWD
+
+if [ x"$FILES"x != xx ]; then
+    echo "error: found TABs in the following files:"
+    for n in $FILES; do
+        echo $n
+    done
+    exit -1
+fi

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all mostlyclean clean install zip avail unavail bin lib doc html info samples test util
+.PHONY: all mostlyclean clean install zip avail unavail bin lib doc html info samples test util check
 
 .SUFFIXES:
 
@@ -24,6 +24,9 @@ samples:
 test:
 	@$(MAKE) -C test    --no-print-directory $@
 
+check:
+	@$(MAKE) -C .github/checks --no-print-directory $@
+
 util:
 	@$(MAKE) -C util    --no-print-directory $@