Default to infinite stack size (#8189)

When servicing a stack overflows, only throw an exception to the given
thread if the user explicitly set a max stack size, using +RTS -K.
Otherwise just service it normally and grow the stack.

In case we actually run out of *heap* (stack chuncks are allocated on
the heap), then we need to bail by calling the stackOverflow() hook and
exit immediately.

Authored-by: Ben Gamari <bgamari.foss@gmail.com>
Signed-off-by: Austin Seipp <aseipp@pobox.com>