Do not use struct fd_set uninitialized (always FD_ZERO() them, before using FD_SET() on a new one, or reusing them after select()). Fixes a segfault on solaris

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@13125 d0543943-73ff-0310-b7d9-9358b9ac24b2