tags: Add the ability to make tags for all archs using "all"

make ALLSOURCE_ARCHS=all tags
- Document this in kbuild.txt
Without this change you have to type each arch separately.

Signed-off-by: John Kacur <[e-mail]>
Signed-off-by: Michal Marek <[e-mail]>

Documentation/kbuild/kbuild.txt

···
 to be included in the databases, separated by blank space. E.g.:
 
     $ make ALLSOURCE_ARCHS="x86 mips arm" tags
+
+To get all available archs you can also specify all. E.g.:
+
+    $ make ALLSOURCE_ARCHS=all tags

scripts/tags.sh

···
 	tree=${srctree}/
 fi
 
+# Find all available archs
+find_all_archs()
+{
+	ALLSOURCE_ARCHS=""
+	for arch in `ls ${tree}arch`; do
+		ALLSOURCE_ARCHS="${ALLSOURCE_ARCHS} "${arch##\/}
+	done
+}
+
 # Detect if ALLSOURCE_ARCHS is set. If not, we assume SRCARCH
 if [ "${ALLSOURCE_ARCHS}" = "" ]; then
 	ALLSOURCE_ARCHS=${SRCARCH}
+elif [ "${ALLSOURCE_ARCHS}" = "all" ]; then
+	find_all_archs
 fi
 
 # find sources in arch/$ARCH