resolve symlinks to Unix domain sockets
Raindrops currently fails when provided a symlink to a socket.
As this is a common practice for many deployment tools (Vlad,
etc.) this patch adds support for finding the realpath prior to
looking the socket up in /proc/net/unix
[ew: commit message subject]
[ew: fixed test to pass under 1.9.3 and 1.8.7:
* Tempfile#unlink is unsafe to call if we want to reuse the
path, use File.unlink(tmp.path) instead
* The return value of File.symlink is zero (or it raises),
so it's unusable.
* File.symlink will not call #to_path under 1.8.7, so it's
necessary to pass pathnames to it, not Tempfile objects.
]
Signed-off-by: Eric Wong <normalperson@yhbt.net>