Update cpp-jsonnet reference to match git submodule version
Update cpp-jsonnet reference to match git submodule version

Unlike naive `go build`, bazel builds generate `astgen/stdast.go` on
the fly from cpp_jsonnet's stdlib.  Cool.

Previously however, the cpp_jsonnet versions in git submodule (used by
naive `go build`) and bazel `http_archive` declarations were not in
sync.  Not so cool.

This meant `bazel test //:go_default_test` failed on
`TestEval/testdata/stdlib_smoke_test`, since the stale bazel
cpp_jsonnet version lacked `std.get`.

This PR updates cpp-jsonnet to match git submodule version.

google/go-jsonnet,google/go-jsonnet,google/go-jsonnet,google/go-jsonnet,google/go-jsonnet