dpkg-dev: install deb-origin.5 in package

Commit 4007271e13b93de69ca566d3c01075acdad0827e forgot to install
the new deb-origin.5 file in the dpkg-dev package.

debian/dpkg-dev.manpages

@@ -6,6 +6,8 @@ debian/tmp/usr/share/man/*/*/deb-version.5
 debian/tmp/usr/share/man/*/deb-version.5
 debian/tmp/usr/share/man/*/*/deb-substvars.5
 debian/tmp/usr/share/man/*/deb-substvars.5
+debian/tmp/usr/share/man/*/*/deb-origin.5
+debian/tmp/usr/share/man/*/deb-origin.5
 debian/tmp/usr/share/man/*/*/deb-override.5
 debian/tmp/usr/share/man/*/deb-override.5
 debian/tmp/usr/share/man/*/*/deb-extra-override.5