MFC r240403 (obrien):

MFC r240403 (obrien):
  Not all Pmake derivatives silently handle empty shell output, so ensure
  there is something for make(1) to consume.  Bmake gives output such as:
  "warning: Couldn't read shell's output for "/bin/sh -c true"

Approved by:	kib (mentor)

git-svn-id: svn://svn.freebsd.org/base/stable/9@251653 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f