Fix build process so that subdir failures cause actual failure, even when CFLAGS...

Fix build process so that subdir failures cause actual failure, even when CFLAGS have a k somewhere...

	* Makefile.am (beta): Use -w MAKEFLAGS instead of RECURSIVE_MAKE_ARGS
	* Makefile.am (time-beta): Ditto.
	* Makefile.am (time-all): Ditto.
	* Makefile.am (time-check): Ditto.
	* Makefile.am (build-report): Ditto.
	* Makefile.am (time-build-report): Ditto.
	* PROBLEMS:  Add explanation for failure.

Signed-off-by: Nelson Ferreira <nelson.ferreira@ieee.org>