Makefile: Enable more warnings for host utilities / tests

This patch adds a bunch of more warnings that are already enabled in
coreboot and thus already enabled for firmware builds anyway (because
coreboot just passes its CFLAGS through). Enabling it in the vboot
Makefile means they also apply to host utilities and tests, which sounds
desirable for consistency.

Fix enough of the cruft and bad coding practices that accumulated over
the years of not having warnings enabled to get it to build again (this
includes making functions static, removing dead code, cleaning up
prototypes, etc.).

Also remove -fno-strict-aliasing from the x86 firmware build options,
because it's not clear why it's there (coreboot isn't doing this, so
presumably it's not needed).

BRANCH=None
BUG=None
TEST=make runtests

Change-Id: Ie4a42083c4770a4eca133b22725be9ba85b24184
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1598721
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
68 files changed