devel/simgear: Use expat from ports instead of internal version
That prepares the port for the upcoming update of textproc/expat2.
As a consequence, Simgear is now provided as a shared library (only). That
commit chases dependencies to Simgear and fixes them for dependent ports .
Submitted by: Sergei Vyshenski <email@example.com>
Approved by: portmgr blanket