Log Message:
Update GNU make to 4.2.1.

Version 4.2.1 (10 Jun 2016)

A complete list of bugs fixed in this version is available here:

http://sv.gnu.org/bugs/index.php?group=make&report_id=111&fix_release_id=107&set=custom

This release is a bug-fix release.

Version 4.2 (22 May 2016)

A complete list of bugs fixed in this version is available here:

http://sv.gnu.org/bugs/index.php?group=make&report_id=111&fix_release_id=106&set=custom

* New variable: $(.SHELLSTATUS) is set to the exit status of the last != or
  $(shell ...) function invoked in this instance of make.  This will be \ 
"0" if
  successful or not "0" if not successful.  The variable value is \ 
unset if no
  != or $(shell ...) function has been invoked.

* The $(file ...) function can now read from a file with $(file <FILE).
  The function is expanded to the contents of the file.  The contents are
  expanded verbatim except that the final newline, if any, is stripped.

* The makefile line numbers shown by GNU make now point directly to the
  specific line in the recipe where the failure or warning occurred.
  Sample changes suggested by Brian Vandenberg <phantall@gmail.com>

* The interface to GNU make's "jobserver" is stable as documented in the
  manual, for tools which may want to access it.

  WARNING: Backward-incompatibility! The internal-only command line option
  --jobserver-fds has been renamed for publishing, to --jobserver-auth.

* The amount of parallelism can be determined by querying MAKEFLAGS, even when
  the job server is enabled (previously MAKEFLAGS would always contain only
  "-j", with no number, when job server was enabled).