This patch fixes a corner-case of ld.a emulation.  ld.a should be
emulated such that it always loads a misaligned value and clears the
corresponding ALAT entry.  The old emulation was correct for the case
where ld.a was followed by ld.c/chk.a (since ALAT entry was cleared),
but wrong for the case where it _wasn't_ followed by ld.c/chk.a.  In
that case, the misaligned value wasn't read from memory, as it should
have been.