Cannot compile on SunOS

[matthiasg]

configure: error: unknown OS type: SunOS

It seems SunOS(Solaris, SmartOS) is not supported yet, is this generally planned or should it actually work and is just missing from the configure?

[sanxiyn]

Ping @notmatt on status of https://github.com/notmatt/rust/commits/smartos.