Replace CVT implementation with libxcvt
libxcvt is a library providing a standalone version of the X server implementation of the VESA CVT standard timing modelines generator.
libxcvt also provides a standalone version of the command line tool
cvt copied from the Xorg implementation and is meant to be a direct replacement to the version provided by the
libcvt can currently be found here: https://gitlab.freedesktop.org/xorg/lib/libxcvt