Remove %clean section

None of currently supported distributions need that.
Last one was EL5 which is EOL for a while.

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

linux-libertine-fonts.spec

@@ -95,9 +95,6 @@ install -Dm 0644 -p %{SOURCE4} \
 install -Dm 0644 -p %{SOURCE5} \
         %{buildroot}%{_datadir}/appdata/biolinum.metainfo.xml
 
-%clean
-rm -fr %{buildroot}
-
 %files common
 %defattr(0644, root, root, 0755)
 %doc Bugs.txt ChangeLog.txt GPL.txt LICENCE.txt OFL-1.1.txt Readme-TEX.txt README