For i386 specifically, this allows using the host GCC
to compile the i386 tests.  But, it should really be
done for all targets, unless we want to pass $(EXTRA_CFLAGS)
directly as part of $(CC).
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20190807143523.15917-2-pbonzini@redhat.com>
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>