Add existing libgroove-git package
Update libgroove-git package

* Add pkg-config config file to list of sources and make PKGBUILD install it.
* Shorten pkgdesc. Make it match the libgroove pkgdesc.
* List epitron as a contributor and myself as the maintainer.
* Make `package` function install a license file and the pkg-config config file.
* Add a vim directive to the end of the file.
* Use sha256sums instead of md5sums.
* Make formatting changes: Use spaces instead of tabs, use single quotes instead
  of double quotes whenever possible, drop quotes entirely when possible and
  reorder variable declarations.
Use libgroove.pc from source code

Drop the `libgroove.pc` file from the libgroove package. Instead of shipping a
pkg-config config file with the package itself, use the pkg-config file provided
in the source code. This change makes it less likely that the pkg-config config
file and package itself will advertise different versions, and it makes the
pkg-config config file more likely to stay up-to-date with upstream.