We don't have rules.mk.in, so autoconf/m4/sed will overwrite the good

rules.mk with a blank file.

This gets us building again.  From what I see of rbb's libtool 1.4 commit,
I didn't see any change to rules.mk that would require variable
substitution.  Ryan?


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@90485 13f79535-47bb-0310-9956-ffa450edef68