fix the magic line to be able to extend the tags file using ctags

[osa1]

After this change I was able to use ctags to add some tags from C files to fast-tags generated tags files.

[elaforge]

Can you verify that vim will still recognize this as an indicator to use bsearch? I got this line from the example on

:help tags-file-format
/_TAG_FILE

The example uses a trailing ~ but doesn't document what it means or if it's required. Also since this is such an obscure thing, could you put a comment saying that for inscrutable reasons this makes ctags recognize the line and vim is still ok with it? Provided that's true of course :)

[osa1]

Yeah vim recognizes this, I'm also a vim user. tags-file-format says this: !_TAG_FILE_SORTED<Tab>1<Tab>{anything} so anything is OK after a tab.

[elaforge]

Ok sounds good. Comment?

[osa1]

Done.

[elaforge]

great, thanks!