MFC r274618,r276521:

MFC r274618,r276521:

MFC Note: text corrected for r274618

r274618:

  Add reachover Makefiles for contrib/netbsd-tests/lib/msun

  A variant of this code has been tested on amd64/i386 for some time by
  EMC/Isilon on 10-STABLE/11-CURRENT. It builds on other architectures, but the
  code will remain off until it's proven it works on virtual hardware or real
  hardware on other architectures

  Sponsored by: EMC / Isilon Storage Division

r276521:

  Reset errno in :scalbnf_val and :scalbnl_val before running the tests so the
  tested errno isn't stale

  This was needed in order for the test to pass on amd64 with stable/10

git-svn-id: svn://svn.freebsd.org/base/stable/10@276672 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f