[PATCH] Move estimateStackSize from ARM into MachineFunction

[Tim Northover]

> Please review this patch which moves the estimateStackSize
> function from the ARM backend into MachineFunction.

A very good idea that I should have done myself. The changes to
estimateFrameSize look trivial and trivially correct to me.

It's a bit cheeky, but I don't suppose you could make AArch64 use the
generic one too? Our implementation is identical to ARM's,
byte-for-byte.

Go for it regardless.

Cheers.

Tim.