Pass classpath to d8

d8 requires the full classpath if --min-api requires default method
or try-with-resources desugaring.  Always pass the full classpath,
since it will already have been built to generate the input jar.

Bug: 116243313
Test: m checkbuild
Change-Id: I363b4d3145e23d4eed77455c1897430206f3ac22