[analyzer] When creating a temporary object, properly copy the value into it.

Adjustments should be considered properly; we should copy the unadjusted object
over the whole temporary base region. If the unadjusted object is no longer
available in the Environment, invalidate the temporary base region, and then
copy the adjusted object into the adjusted sub-region of the temporary region.

This fixes a regression introduced by r288263, that caused various
false positives, due to copying only adjusted object into the adjusted region;
the rest of the base region therefore remained undefined.
Before r288263, the adjusted value was copied over the unadjusted region,
which is incorrect, but accidentally worked better due to how region store
disregards compound value bindings to non-base regions.

An additional test machinery is introduced to make sure that despite making
two binds, we only notify checkers once for both of them, without exposing
the partially copied objects.

This fix is a hack over a hack. The proper fix would be to model C++ temporaries
in the CFG, and after that dealing with adjustments would no longer be
necessary, and the values we need would no longer disappear from the
Environment.

rdar://problem/30658168

Differential Revision: https://reviews.llvm.org/D30534

llvm-svn: 298924