[analyzer][NFC] Document getVarRegion shortcomings (#191168)
... more precisely, that the analyzer currently uses `NonParamVarRegion`
instances to represent parameters of the entrypoint stack frame and
parameters that are captured by inner lambdas or blocks.
In my recent commit f40c234191802154d5b3fc3209908c3f2d6e1649 I added a
FIXME note to the method `MemRegionManager::getVarRegion`, but now, as I
tried to implement that I realized that the situation is more complex.
As I don't have time to fix this right now, I'm pushing this commit to
remove the inaccurate FIXME and replace it with more accurate TODO notes
that explain the current (problematic) behavior of the codebase.
llvm-project
b66fbb1f - [analyzer][NFC] Document getVarRegion shortcomings (#191168)
