Import proper fix for misc/49356 (/usr/include/atf-c/config.h) after atf-c/config.h
was removed from the build

Pointyhat to: me (again, for not running make delete-old after running test builds)


git-svn-id: svn+ssh://svn.freebsd.org/base/head@274079 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f