rpm: fix compatibility with RPM 4.20

[vashirov]

Issue Description
RPM 4.20 drops support for the deprecated %patchN syntax [1], and adds a build-specific path to %_builddir [2]

Bundled libdb spec file was updated to use the new %patch syntax [3], but it was after the spec file was imported.

[1] rpm-software-management/rpm@afd3524
[2] rpm-software-management/rpm@9d35c8d
[3] https://src.fedoraproject.org/rpms/libdb/c/8ab86f49d4c3039fc6d1ce87c8c6d5579f5bf1e0?branch=rawhide