[lldb] [POSIX-DYLD] Add libraries from initial eTakeSnapshot action

Explicitly consider the libraries reported on the initial eTakeSnapshot
action added, through adding them to the added soentry list
in DYLDRendezvous::SaveSOEntriesFromRemote().  This is necessary
on FreeBSD since the dynamic loader issues only a single 'consistent'
state rendezvous breakpoint hit for all the libraries present
in DT_NEEDED (while Linux issues an added-consistent event pair).

Reenable memory maps on FreeBSD since this fixed the issue triggered
by them.

Differential Revision: https://reviews.llvm.org/D92187