Rebuild Makefile.in with automake 1.14

The Makefile.in generated from automake 1.14 is backward compatible, but
not forward compatible. This allows it to build on more systems, such as
Arch and OS X.
Homebrew installation

This can be installed using Homebrew for OS X.

    brew tap mike-burns/rcm
    brew install rcm
Add Arch PKGBUILD

https://aur.archlinux.org/packages/rcm-git/
Document the Arch installation

SInce Arch users choose from different installation options for
themselves, just link to the AUR page and let them decide.
Add exclude option