kbuild: escape meta characters in regular expression in make TAGS

Alexey Dobriyan <adobriyan@gmail.com> introduced a code adds
menuconfig SOMETHING in Kconfig to tags output when you did "make tags".

See http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=80ff2624



"make tags" may work fine with his code. However make TAGS doesn't work well
because etags command requires backslashes to escape meta characters like
`(', `)' and `|'.

Here is a patch.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>