oleaut32: Add ARM support to DispCallFunc().

[Donna Whisnant]

I just posted v2 of the patch with the requisite changes.

[...]

> Well, with __arm__ you already exclude 64-bit, as this only checks for
> the
> traditional arm32 instruction set. Code in that ifdef won't be
> compiled on arm64. If you want to write code that runs on arm64 you'd
> check
> for __aarch64__ instead of __arm__. see following link for reference:
> https://source.winehq.org/git/wine.git/blob/85527dbdf39c70fe5b1a341701813ecf6263ebc3:/dlls/kernel32/process.c#l217
> 
> 

Interesting!  I didn't realize that that was true about __arm__.  The
majority of my ARM work has been on 32-bit devices.  I have done some
64-bit ARM work, but nothing that needed those defines.

I had looked in the ARM and gcc specs on the defines and my
interpretation of it was that __arm__ was always defined on any ARM
platform (32 or 64) and that on 64 the "__aarch64__" was also defined. 
I didn't realize they are mutually exclusive with __arm__ implying
32-bit.  I must have misinterpreted it.