kbuild: reintroduce ALLSOURCE_ARCHS support for tags/cscope

This patch reintroduce the ALLSOURCE_ARCHS support for tags/TAGS/
cscope targets. The Kbuild previously has this feature, but after
moving the targets into scripts/tags.sh, ALLSOURCE_ARCHS disappears.

It's something like this:

	$ make ALLSOURCE_ARCHS="x86 mips arm" tags cscope

Signed-off-by: Jike Song <albcamus@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Documentation/kbuild/kbuild.txt

@@ -124,3 +124,10 @@ KBUILD_EXTRA_SYMBOLS
 --------------------------------------------------
 For modules use symbols from another modules.
 See more details in modules.txt.
+
+ALLSOURCE_ARCHS
+--------------------------------------------------
+For tags/TAGS/cscope targets, you can specify more than one archs
+to be included in the databases, separated by blankspace. e.g.
+
+    $ make ALLSOURCE_ARCHS="x86 mips arm" tags

scripts/tags.sh

@@ -24,6 +24,11 @@ else
 	tree=${srctree}/
 fi
 
+# Detect if ALLSOURCE_ARCHS is set. If not, we assume SRCARCH
+if [ "${ALLSOURCE_ARCHS}" = "" ]; then
+	ALLSOURCE_ARCHS=${SRCARCH}
+fi
+
 # find sources in arch/$ARCH
 find_arch_sources()
 {
@@ -54,26 +59,29 @@ find_other_sources()
 find_sources()
 {
 	find_arch_sources $1 "$2"
-	find_include_sources "$2"
-	find_other_sources "$2"
 }
 
 all_sources()
 {
-	find_sources $SRCARCH '*.[chS]'
+	for arch in $ALLSOURCE_ARCHS
+	do
+		find_sources $arch '*.[chS]'
+	done
 	if [ ! -z "$archinclude" ]; then
 		find_arch_include_sources $archinclude '*.[chS]'
 	fi
+	find_include_sources '*.[chS]'
+	find_other_sources '*.[chS]'
 }
 
 all_kconfigs()
 {
-	find_sources $SRCARCH 'Kconfig*'
+	find_sources $ALLSOURCE_ARCHS 'Kconfig*'
 }
 
 all_defconfigs()
 {
-	find_sources $SRCARCH "defconfig"
+	find_sources $ALLSOURCE_ARCHS "defconfig"
 }
 
 docscope()