This patch insures to properly use the value of GetBuildDir or the build_dir parameters as a relative pathname.  Note,
that when using (the new) SetBuildDir with a relative pathname, this pathname will be relative to the current directory
at the time of calling CompileMacro and not at the time of calling SetBuildDir.
I added ACLiC.BuildDir to rootrc.in


git-svn-id: http://root.cern.ch/svn/root/trunk@6479 27541ba8-7e3a-0410-8455-c3a389f83636