gitweb: fix 'ctags' feature check and others

gitweb: fix 'ctags' feature check and others

gitweb_check_feature() function is to retrieve the configuration parameter
list and calling it in the scalar context does not give its first element
that tells if the feature is enabled.  This fixes all the existing callers
to call the function correctly in the list context.

Signed-off-by: Junio C Hamano <redacted>