use %{buildroot} consistently

libwpg.spec

@@ -72,10 +72,10 @@ help2man -N -n 'batch convert WordPerfect Graphics files into SVG' \
     -o wpg2svgbatch.pl.1 ./src/conv/svg/wpg2svgbatch.pl
 
 %install
-make install DESTDIR=$RPM_BUILD_ROOT
-find $RPM_BUILD_ROOT -name '*.la' -exec rm -f {} ';'
+make install DESTDIR=%{buildroot}
+find %{buildroot} -name '*.la' -exec rm -f {} ';'
 # we install API docs directly from build
-rm -rf $RPM_BUILD_ROOT/%{_docdir}/%{name}
+rm -rf %{buildroot}/%{_docdir}/%{name}
 
 install -m 0755 -d %{buildroot}/%{_mandir}/man1
 install -m 0644 wpg2*.1 %{buildroot}/%{_mandir}/man1