Improve handling of durability of ClassAd logs.  #4283

This switches fsync to fdatasync where possible.  Also, ensure we
fsync the parent directory after performing rename().
Fixes and improvements from code review. #4283
Add in fake condor_fdatasync for libcondorapi. #4283
Make handling of multiline search results on windows not hand off a
multiline result as we were for java searches. Turn on new security
issue regression test "cmd_q_protocols" and make cmd_gpu_discovery more
verbose for now. #3594
Merge branch 'V8_2-branch'
Look in headers, not libc, for fdatasync.  #4283

Mac OS X is a curious platform.  Its libc provides fdatasync as
a symbol we can link against, but the headers we use don't actually
define fdatasync.  Hence, the build is failing because the CMake
test succeeds though condor_fsync.cpp doesn't compile.

So, we switch the cmake test from looking at libc to the unistd.h
header for fdatasync.  This will disable use of fdatasync on Mac
OS X - but fix the build.
Need more information to track possible race condition #3594
in concurrency tests.
Merge branch 'V8_2-branch'
edit 8.3.0 version history item #4283
Merge branch 'master' of /p/condor/repository/CONDOR_SRC
fix linux hyperthread detection in sysapi #4458
===VersionHistory:Pending===
no ticket for these edits of manual doc on cgroup tracking
add -absent to usage #2690
Merge branch 'V8_2-branch'
found 2 more references to PrivSep in the manual.  Gone now.  #4057
Merge branch 'V8_2-branch' of /p/condor/repository/CONDOR_SRC into V8_2-branch
Merge branch 'V8_2-branch'

Conflicts:
	doc/admin-man/group-tracking.tex
did not properly fix ALL merge conflicts before previous commit.
If oom_control can't be written, still try to catch OOM events. #4435

This is a short term workaround until we understand what the
kernel is really doing.
Document #4435