am 3b74eb32: Merge remote-tracking branch \'upstream/master\' into libcxx4

* commit '3b74eb32545456120f507d5dc2b74d11a3b89bb0': (1404 commits)
  Initial empty repository
  Use defined(__APPLE__) rather than __APPLE__
  ARM64: compare RTTI names as strings
  ARM64: use the alternate string layout on Apple platforms.
  [libc++] Teach is_integral, is_[un]signed and make_[un]signed about __[u]int128_t
  Implement LWG issue #2135. If something goes wrong in condition_variable::wait, call terminate() rather than throwing an error. Do this indirectly, by marking the call as 'noexcept'. This is better than just calling terminate() directly, because it gives a better error message on the console.
  Add tests that should fail when lock() throws. THis is part of LWG issue #2135. No library changes here.
  Mark LWG issues #2075 and #2142 as complete. 2142 was a change to the standard to remove redundant wording, which required no changes to libc++. 2075 was a rewrite of the requirements for forward progress, and again, requires no changes to the library.
  Add a test to make sure we're doing the right thing for throwing exceptions from deferred functions. This is LWG issue #2186. No change to the library needed.
  Mark LWG Issue #2288 as complete. This was wording cleanup, no code changes required. Also mark #2104 as complete. Leave the implementation in libc++ as noexcept, since implementations are allowed to add noexcept to non-virtual calls. If we throw from unique_lock& operator=(unique_lock&& u), then that means the preconditions were violated, and calling terminate() (as a result of throwing from a noexcept function) is as good example of undefined behavior as any other.
  Minor cleanup from r204078; remove two empty test directories that were left behind.
  Implement N3891: A proposal to rename shared_mutex to shared_timed_mutex
  Replace a tab with a space
  Remove Issue #2235 from the Chicago section. The resolution was approved in Bristol (and it is listed there), and then is was approved *again* in Chicago. Thanks to STL @ microsoft for the catch
  Exclude .svn (and other "dot" directories) when installing headers.
  build: remove unnecessary modification of CMAKE_REQUIRED_DEFINITIONS
  build: fix erroneous overwriting of flags
  build: fix add_definition abuse in CMake
  build: remove an errant comma
  THIRD TIME. Richard pointed out (again) that I'd switched the order of the instance variables; and thus failed to repair the ABI break. After this, I'm going to sit down and watch TV for the evening.
  ...