add error checking on overflow in allocation for MAYBE_STACK_ALLOC
add error checking on overflow in allocation for MAYBE_STACK_ALLOC

hildeth/chapel,hildeth/chapel,CoryMcCartan/chapel,chizarlicious/chapel,chizarlicious/chapel,chizarlicious/chapel,CoryMcCartan/chapel,hildeth/chapel,hildeth/chapel,chizarlicious/chapel,hildeth/chapel,chizarlicious/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,chizarlicious/chapel,hildeth/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,chizarlicious/chapel,hildeth/chapel,CoryMcCartan/chapel