rpm question - expand var in 'hereis' doc

[Neal Becker <ndbecker2 gmail com>]

In a spec file:

# Create pkgconfig file
cat > emacs.pc << EOF
sitepkglispdir=%{site_lisp}
sitestartdir=%{site_lisp}/site-start.d

The value of %{site_lisp} is not expanded when written into the file.  How do I fix this?