Work on a BSD/OS system where GNU make is used instead of the native

make.

Roy suggests using the variable set by AC_PROG_MAKE; we don't use that
yet, though I guess we could.  Greg suggests leaving this to Roy since
he will revamp this stuff soon anyway.

Inspired by: Joe Orton's patch to APR to accomplish the same thing


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@88286 13f79535-47bb-0310-9956-ffa450edef68