translate-all: add DEBUG_LOCKING asserts

This adds asserts to check the locking on the various translation
engines structures. There are two sets of structures that are protected
by locks.

The first the l1map and PageDesc structures used to track which
translation blocks are associated with which physical addresses. In
user-mode this is covered by the mmap_lock.

The second case are TB context related structures which are protected by
tb_lock which is also user-mode only.

Currently the asserts do nothing in SoftMMU mode but this will change
for MTTCG.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20161027151030.20863-4-alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
