[PATCH, RFC] etags/ctags v22.0.92 break Linux kernel `make TAGS/tags`

[Don Mullis]

`make TAGS` produces a TAGS that causes the emacs v22.0.92 command 
'M-x tags-search' to repeatedly stop with complaints about missing files.
Proximate cause of this is "#line" directives in Linux source files.

`make tags` produces hundreds of lines of complaints about duplicate
entries.

The following ugly patch works around these problems.  Posting to
both kbuild-devel and emacs-devel in hopes something better can be worked out
for the Emacs v22 release.

---
 Makefile |   12 ++++++++++++
 1 file changed, 12 insertions(+)

Index: linux-2.6/Makefile
===================================================================
--- linux-2.6.orig/Makefile
+++ linux-2.6/Makefile
@@ -1337,6 +1337,18 @@ define xtags
                --langdef=dotconfig \
                --language-force=dotconfig \
                --regex-dotconfig='/^#?[[:blank:]]*(CONFIG_[[:alnum:]_]+)/\1/'; 
\
+       elif $1 --version 2>&1 | grep -iq 'ctags.* 22\.'; then \
+           $(all-sources) | xargs $1 -a -w; \
+           $(all-kconfigs) | xargs $1 -a -w \
+               --regex='/^[ \t]*config[ \t]+\([a-zA-Z0-9_]+\)/\1/'; \
+           $(all-defconfigs) | xargs -r $1 -a -w \
+               --regex='/^#?[ \t]?\(CONFIG_[a-zA-Z0-9_]+\)/\1/'; \
+       elif $1 --version 2>&1 | grep -iq 'etags.* 22\.'; then \
+           $(all-sources) | xargs $1 -a --no-line-directive; \
+           $(all-kconfigs) | xargs $1 -a --no-line-directive \
+               --regex='/^[ \t]*config[ \t]+\([a-zA-Z0-9_]+\)/\1/'; \
+           $(all-defconfigs) | xargs -r $1 -a --no-line-directive \
+               --regex='/^#?[ \t]?\(CONFIG_[a-zA-Z0-9_]+\)/\1/'; \
        elif $1 --version 2>&1 | grep -iq emacs; then \
            $(all-sources) | xargs $1 -a; \
            $(all-kconfigs) | xargs $1 -a \