Add support for RHEL/CentOS 8

The --enablerepo=PowerTools option fixes:

sudo yum install gcc gcc-c++ automake autoconf libtool gettext-devel make cmake bison flex yasm pkgconfig gtk-doc curl doxygen texinfo texinfo-tex texlive-dvips docbook-style-xsl transfig intltool rpm-build redhat-rpm-config python3-devel libXrender-devel pulseaudio\
-libs-devel libXv-devel mesa-libGL-devel libXcomposite-devel alsa-lib-devel perl-ExtUtils-MakeMaker libXi-devel perl-XML-Simple gperf gdk-pixbuf2-devel wget docbook-utils-pdf glib-networking help2man dbus-devel glib2-devel libXrandr-devel libXtst-devel git subversio\
n xorg-x11-util-macros mesa-libEGL-devel ccache openssl-devel chrpath fuse-devel
Failed to set locale, defaulting to C
Last metadata expiration check: 0:26:19 ago on Fri Oct 25 08:48:02 2019.
No match for argument: yasm
Package pkgconf-pkg-config-1.4.2-1.el8.x86_64 is already installed.
No match for argument: gtk-doc
Package curl-7.61.1-8.el8.x86_64 is already installed.
No match for argument: doxygen
No match for argument: texinfo
No match for argument: texinfo-tex
No match for argument: transfig
No match for argument: gperf
No match for argument: docbook-utils-pdf
No match for argument: help2man
Package git-2.18.1-3.el8.x86_64 is already installed.
No match for argument: xorg-x11-util-macros
Error: Unable to find a match