heap overflow should generate an exception

Heap overflow should produce a HeapOverflow exception that can be caught, rather than shutting down the entire RTS immediately.

[Original ticket description follows. The submitter happened to expose another bug, which was that heap overflow was not detected at all when a single allocation exceeded the maximum heap size. The program below now exits with a "Heap exhausted" message.]

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I want to use the -M option for the goals that are stated in the manual.

./TestProgram +RTS -M5m -RTS 

Expected output:

Something like "out of heap space"

Actual result:

Machine going into a state where it swaps memory 

This is the code for TestProgram:

import Control.Monad.ST 
import Data.Array.ST
import Data.Array.MArray
import Data.Array.Base(unsafeNewArray_)
main = print (runST (do make_empty_table >> return ()))

make_empty_table::  ST s (STArray s (Int, Int) (Maybe ep))
make_empty_table = 
       unsafeNewArray_ ((1, 1), (16384, 16384))

This was tested with 6.9.20071018 on an athlon-xp, and confirmed by dcoutts also on x86-64 with ghc-6.8.0.20071015.