x11/xkeyboard-config: Update to 2.29

Update xkeyboard-config to 2.29
Upstream has switched to use python to generate certan things during build,
add a build dependency on on python3.5+.
Change MASTER_SITES to actually work now that XORG_CAT is no more, this
should fix fetch. Previously it pulled from distcache.
Try to fix the optional etersoft symbols patch.