Jul 25あたりに更新された
source/x/x11/patch/xorg-server.patch
で
source/x/x11/patch/xorg-server/hogehogehoge.patch
を当てると

#sh x11.SlackBuild xserver

でこける
make[2]: Entering directory '/tmp/x11-build/xorg-server-1.20.0/hw/xfree86'
cd ../.. && /bin/sh /tmp/x11-build/xorg-server-1.20.0/missing automake-1.15 --foreign hw/xfree86/Makefile
/tmp/x11-build/xorg-server-1.20.0/missing: line 81: automake-1.15: command not found
WARNING: 'automake-1.15' is missing on your system.
You should only need it if you modified 'Makefile.am' or
'configure.ac' or m4 files included by 'configure.ac'.
The 'automake' program is part of the GNU Automake package:
<http://www.gnu.org/software/automake>;
It also requires GNU Autoconf, GNU m4 and Perl in order to run:
<http://www.gnu.org/software/autoconf>;
<http://www.gnu.org/software/m4/>;
<http://www.perl.org/>;
make[2]: *** [Makefile:681: Makefile.in] Error 127
make[2]: Leaving directory '/tmp/x11-build/xorg-server-1.20.0/hw/xfree86'
make[1]: *** [Makefile:615: all-recursive] Error 1
make[1]: Leaving directory '/tmp/x11-build/xorg-server-1.20.0/hw'
make: *** [Makefile:816: all-recursive] Error 1


以前の
source/x/x11/patch/xorg-server.patch
に差し替えるだけでビルドできる