Fix spurious error on TAGS target when missing defconfig

[David Gibson <david@gibson.dropbear.id.au>]

Andrew, please apply:

Not all architectures have a file named 'defconfig' (e.g. powerpc).
However the make TAGS and make tags targets search such files for
tags, causing an error message when they don't exist.  This patch
addresses the problem by instructing xargs not to run the tags program
if there are no matching files.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Index: working-2.6/Makefile
===================================================================
--- working-2.6.orig/Makefile	2006-10-03 13:35:19.000000000 +1000
+++ working-2.6/Makefile	2006-10-03 13:41:08.000000000 +1000
@@ -1321,7 +1321,7 @@ define xtags
 		--langdef=kconfig \
 		--language-force=kconfig \
 		--regex-kconfig='/^[[:blank:]]*config[[:blank:]]+([[:alnum:]_]+)/\1/'; \
-	    $(all-defconfigs) | xargs $1 -a \
+	    $(all-defconfigs) | xargs -r $1 -a \
 		--langdef=dotconfig \
 		--language-force=dotconfig \
 		--regex-dotconfig='/^#?[[:blank:]]*(CONFIG_[[:alnum:]_]+)/\1/'; \
@@ -1329,7 +1329,7 @@ define xtags
 	    $(all-sources) | xargs $1 -a; \
 	    $(all-kconfigs) | xargs $1 -a \
 		--regex='/^[ \t]*config[ \t]+\([a-zA-Z0-9_]+\)/\1/'; \
-	    $(all-defconfigs) | xargs $1 -a \
+	    $(all-defconfigs) | xargs -r $1 -a \
 		--regex='/^#?[ \t]?\(CONFIG_[a-zA-Z0-9_]+\)/\1/'; \
 	else \
 	    $(all-sources) | xargs $1 -a; \

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson