Remove unused hostname resolution in shm plugins and aserver

Remove unused hostname resolution in shm plugins and aserver

PCM and control shm plugins and aserver have some codes to resolve the
host address and check whether it's a local host although the given
address is never used.  In addition, the code contains gethostbyname()
that is known to be obsoleted.  So, let's get rid of all these unused
codes.

The host configuration item is still accepted (but just ignored) for
keeping the compatibility.

Signed-off-by: Takashi Iwai <tiwai@suse.de>