The codegen backend is faster than the template backend, even for
modules that don't use IOS. On x64 we see the template backend being
4% slower for TGS requests using the kdc-tester program.
So let's build both, libasn1 (codegen) and libasn1template when
configured with --disable-asn1-templating, but make sure that the
asn1_print utility is linked with libasn1template.
Eventually we'll want to either optimize the template backend better,
or add IOS and JSON printing support to the codegen backend.