Remove configure check for X11 keysym files

Remove configure check for X11 keysym files

Since every user building the library, even from git, doesn't need these
files anymore, there's no need to check for them (this goes for makekeys
as well).

The only remaining user is the update-keysyms target, but whoever will
run it again (if ever) will probably know what he's doing (at least
enough to run git diff before git commit). And the defaults should be
fine too.

Signed-off-by: Ran Benita <ran234@gmail.com>