Fix invalid allocation bug in runtime that allows for segfaults (#2896)
Fix invalid allocation bug in runtime that allows for segfaults (#2896)

Thanks to @malte for identifying the root cause of #2013.

This PR fixes things so that if there's a request for a `size_t`
sized allocation, it actually tries to allocate it instead of
pretending that it allocated it while not actually allocating
anything which results in memory clobbering and segfaults.

resolves #2013
jemc/ponyc,ponylang/ponyc,dipinhora/ponyc,Theodus/ponyc,dipinhora/ponyc,Theodus/ponyc,sgebbie/ponyc,sgebbie/ponyc,jemc/ponyc,kulibali/ponyc,sgebbie/ponyc,cquinn/ponyc,ponylang/ponyc,sgebbie/ponyc,sgebbie/ponyc,ponylang/ponyc,kulibali/ponyc,kulibali/ponyc,Theodus/ponyc,CausalityLtd/ponyc,cquinn/ponyc,Theodus/ponyc,cquinn/ponyc,cquinn/ponyc,kulibali/ponyc,CausalityLtd/ponyc,dipinhora/ponyc,CausalityLtd/ponyc,Theodus/ponyc,jemc/ponyc