Clean up some obsolete Autoconf code

Clean up some obsolete Autoconf code

Remove hand-crafted equivalents of AC_SEARCH_LIBS for socket, connect,
and gethostbyname functions.  The only effective difference between
this code and AC_SEARCH_LIBS was to define the HAVE_* macros for the
functions, which are not used anywhere in the tree.

Remove AC_FUNC_SETVBUF_REVERSED.  This call no longer does anything in
current versions of Autoconf since the last system with this problem
was based on SVR2 and became obsolete in 1987.  Remove the one place in
the source tree where the results are used.

Reviewed-on: http://gerrit.openafs.org/http://gerrit.openafs.org/154
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>