Fix the broken Travis CI:
1. Update the `tock` submodule to a version that includes
https://github.com/tock/tock/pull/2024, which fixes the OpenTitan BootROM
download code, as well as https://github.com/tock/tock/pull/2038, which fixes
a HiFive1 kernel bug.
2. Update the setup-qemu make target to track changes in Tock's makefile.
3. Point `test_runner` to the new QEMU location.
4. Disable the callback test. HiFive1 doesn't have a working timer driver. The
callback test only worked before because of some other callback, which
doesn't seem to occur with the new kernel.
diff --git a/Makefile b/Makefile
index 0227e3d..d47b155 100644
--- a/Makefile
+++ b/Makefile
@@ -68,7 +68,8 @@
.PHONY: test-qemu-hifive
test-qemu-hifive: kernel-hifive
PLATFORM=hifive1 cargo rrv32imac --example libtock_test --features=alloc \
- --features=__internal_disable_gpio_in_integration_test
+ --features=__internal_disable_gpio_in_integration_test \
+ --features=__internal_disable_timer_in_integration_test
cargo run -p test_runner
.PHONY: examples
