On Windows, FS_Win32_Cygwin has been used if a Cygwin Git installation
is present in the PATH. Assuming that the user works with the Cygwin
Git installation may result in unnecessary overhead if he actually
does not.
Applications built on top of jgit may have more knowledge on the
actually used Git client (Cygwin or not) and hence should be able to
configure which FS to use accordingly.
Change-Id: Ifc4278078b298781d55cf5421e9647a21fa5db24
936e4ab2f2