kbproto: Add 'Requires: xproto >= 7.0.33' for _X_NONSTRING usage
Commit 21e05da9 made the XKB headers depend on the definition
of _X_NONSTRING
added in commit 50671520 which raised the
version in the xproto.pc
to 7.0.33. While this is automatically
handled for those using unmodified upstream xorgproto releases, adding
this may help make it easier to diagnose errors like those reported in
issue #51 (closed) where headers are being mixed across releases.
Signed-off-by: Alan Coopersmith