linux-wandboard

kbuild: Add ctags support for function prototypes and external variable declarations

This patch adds function prototypes and external variable declarations
to the set of tag kinds when running ctags. I find this useful when
perusing the kernel. Please apply.

Signed-off-by: John Kacur <jkacur@rogers.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>