Fix build with rpm 4.20

rpm 4.20 now uses a build-specific %_builddir (previously %_topdir/BUILD),
but this directory change occurs by default even in older versions.

https://github.com/rpm-software-management/rpm/issues/2078

nodejs-packaging.spec

@@ -52,10 +52,8 @@ It generates a bundled license file that gets the licenses in the runtime
 dependency tarball
 
 %prep
-pushd %{_topdir}/BUILD
 cp -da %{_sourcedir}/* .
 tar xvf test.tar.gz
-popd
 
 
 %build