ruby19 opportunistically links with libffi

[macports@…]

Ruby 1.9.2's bundled extension fiddle.bundle is linked to libffi. Please consider making ruby19 port have dependency on libffi.

When libffi port *is not* installed:

$ otool -L /opt/local/lib/ruby1.9/1.9.1/x86_64-darwin10.4.0/fiddle.bundle
/opt/local/lib/ruby1.9/1.9.1/x86_64-darwin10.4.0/fiddle.bundle:
        /opt/local/lib/libruby.1.9.1.dylib (compatibility version 1.9.1, current version 1.9.1)
        /usr/lib/libffi.dylib (compatibility version 1.0.0, current version 1.0.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.0)
        /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 227.0.0)

When libffi port *is* installed:

$ otool -L /opt/local/lib/ruby1.9/1.9.1/x86_64-darwin10.4.0/fiddle.bundle
/opt/local/lib/ruby1.9/1.9.1/x86_64-darwin10.4.0/fiddle.bundle:
	/opt/local/lib/libruby.1.9.1.dylib (compatibility version 1.9.1, current version 1.9.1)
	/opt/local/lib/libffi.5.dylib (compatibility version 6.0.0, current version 6.10.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.0)
	/usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 227.0.0)

[ryandesign@…]

Please add the dependency on libffi, or make ruby19 not link with MacPorts libffi.

[kimuraw@…]

I added port:libffi to depends_lib at r71907. thanks!