Bug#338506: VT switching bug in Xlibs or xserver-xorg

[Neil Turton <neilt+bugs@chiark.greenend.org.uk>]

I've just been bitten by this one.  I think there still needs to be
something done since the configuration script accepts "uk" as the
layout without checking if it's valid.  The X server then ignores the
error from xkbcomp without putting anything in Xorg.0.log.  There's
therefore no hint to the user what has gone wrong unless they look at
the messages from stdout/stderr or search for this bug report.

I suggest one or both of the following fixes:
  1. The config script checks the layout given by the user.
  2. The config script uses xkbcomp to verify the keyboard details.

It might be nice to have:
  3. The X server puts a message in Xorg.0.log when xkbcomp fails.
  4. The X server refuses to start when xkbcomp fails.

I don't know what the impact of (4) would be.  There could be some
reason that the error is not treated as fatal.

Cheers, Neil.

Error messages from stderr:
 The XKEYBOARD keymap compiler (xkbcomp) reports:
 > Error:            Can't find file "pc/uk" for symbols include
 >                   Exiting
 >                   Abandoning symbols file "default"
 Errors from xkbcomp are not fatal to the X server