Avoid GCC's "cast from pointer to integer of different size" warning.

This is a bit of a stab in the dark as I'm not sure I've got these
source files compiling correctly locally. (and the warning only
reproduces on a 32bit build anyway)
Register allocator: add condition to hoist a spill to outer loop.

We make sure a spill is not hoisted to a hotter outer loop by adding
a condition. Hoist a spill to outer loop if there are multiple dependents
(it can be beneficial if more than one dependents are hoisted) or
if DepSV (the hoisting source) is hotter than SV (the hoisting destination).

rdar://16268194