crosvm-fuzz: add hypervisor dependency for block_fuzzer
crosvm-fuzz: add hypervisor dependency for block_fuzzer

https://crrev.com/c/3330204 changed the block fuzzer to depend on
hypervisor but did not add the necessary reference to Cargo.toml. Add it
to fix the fuzzer build.

BUG=None
TEST=Build crosvm ebuild with USE=fuzzer

Fixes: 00f1c9fd468d ("Update to the latest pKVM ABI.")
Change-Id: Ic90c6bdd29f87af1c78093a970056467e9c4c36e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3364963
Reviewed-by: Dmitry Torokhov <10a8c465cefc9bdd6c925e26964d23c90f1141cc@chromium.org>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm