Log entry hashtable helpers.
Htab support. Return true if two log entries are the same.
FIXME:
rth: I suggest that we get rid of the component refs etc.
I.e. resolve the reference to base + offset.
We may need to actually finish a merge with mainline for this,
since we'd like to be presented with Richi's MEM_REF_EXPRs more
often than not. But in the meantime your tm_log_entry could save
the results of get_inner_reference.
See: g++.dg/tm/pr46653.C
Special case plain equality because operand_equal_p() below will
return FALSE if the addresses are equal but they have
side-effects (e.g. a volatile address).
References tm_new_mem_map::local_new_memory, and tm_new_mem_map::val.