(FACT-3446) Call close(2) with Solaris FFI

[mhashizume]

Previously, when Facter ran on Solaris it would use shutdown(2) to attempt to close open sockets. However, this would leak file descriptors and occasionally cause an issue where the system would hit its maximum open files.

This commit updates Facter to instead use close(2) on Solaris to ensure that file descriptors are not leaked.

[joshcooper]

For posterity, facter 3 used a scoped_descriptor to manage the socket's lifetime and it called close when the scoped_descriptor went out of scope:

facter/lib/src/util/posix/scoped_descriptor.cc

Line 16 in 6d7ffc6

::close(descriptor);