[lldb] [POSIX-DYLD] Add libraries from initial rendezvous brkpt hit

Explicitly consider the libraries reported on the initial rendezvous
breakpoint hit added.  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.  It is also helpful on Linux
where it ensures that ld-linux is considered loaded as well
as the shared system libraries reported afterwards.

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

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