Update to trafficserver release 4.2.0

* Apply necessary patch for automake makefiles from upstream to link
  correctly.
* Add necessary steps to generate makefiles.
Don't bother removing libtool libraries.

* Don't bother removing libtool libraries.  The 'makepkg' command now
  removes libtool and static libraries by default.  It is also a
  configurable option/argument to 'makepkg'.  Simplify the PKGBUILD
  logic by allowing 'makepkg' to handle any libtool libraries.
Silence warning generated during package upgrade.

* If an older version of the package was already installed 'pacman -U'
  warns that the existing '/run/trafficserver' directory permissions
  differ from the package.  Alter the install logic to ensure the
  directory permissions match those that would be generated by systemd
  tmpfiles.