Add test for denied process attach by pid and fix found bugs in Process/ProcessPOSIX.cpp
and FreeBSD/ProcessMonitor.

http://reviews.llvm.org/D6240


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@222372 91177308-0d34-0410-b5e6-96231b3b80d8