Merge remote-tracking branch 'origin/swift-3.1-branch' into stable

* origin/swift-3.1-branch:
  Revert "Add support for __builtin_os_log_format[_buffer_size]"
  Revert "test/CodeGen/builtins.c: reinstate #ifdef __x86_64__ around __builtin_longjmp"
  Revert "Fix test on non-X86 platforms"
  Revert "Fix handling of %% format specifier in os_log builtins."
  Revert "Fix diagnostic format string for err_os_log_argument_to_big"