MFC r266074,r266104,r266147:

MFC r266074,r266104,r266147:

r266074:

  Move old fmake tests into bmake and hook them to the build.

  This first step is mostly to prevent the code from rotting even further
  and to ensure these do not get wiped when fmake's code is removed from
  the tree.

  These tests are currently being skipped because they detect the underlying
  make is not fmake and thus disable themselves -- and the reason is that
  some of the tests fail, possibly due to legitimate bugs.  Enabling them to
  run against bmake will come separately.

  Lastly, it would be ideal if these tests were fed upstream but they are
  not ready for that yet.  In the interim, just put them under usr.bin/bmake/
  while we sort things out.  The existence of a different unit-tests directory
  within here makes me feel less guilty about this.

  Change confirmed working with a clean amd64 build.

r266104:

  Undo changes to the generated Makefile. Move tests directory to proper
  location, including updating the test to work in the more-fragile
  fmake -> bmake bootstrap environment.

r266147:

  Makefile.inc is also included by the tests subdirectory, which results
  in SUBDIRS having tests added to it, which fails. Work around this by
  checking to make sure tests exists before adding it to subdirs and
  work to get the generated file fixed so we can rename Makefile.inc to
  something else so it isn't automatically included by subdirs...

git-svn-id: svn://svn.freebsd.org/base/stable/10@276389 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f