Eliminate sim_client include of getopt.h

Eliminate sim_client include of getopt.h

Commit 9139a60c94c24e41109574e84e7cda9c2dc3fb38 added an unconditional
include of getopt.h, which is non-portable (it isn't present on HP-UX)
and unecessary for getopt().  The same commit also disabled the
include of unistd.h (which is necessary for getopt()), as sim_client
no longer indirectly includes autoconf.  Make the unistd.h include
unconditional and remove the getopt.h include.

[ghudson@mit.edu: edited commit message]

ticket: 9102 (new)
tags: pullup
target_version: 1.21-next