Test failures on Window 32 bit

Running OpenEXRTest in Visual Studio 2022 in 32 bit mode will cause multiple test failures.

One example:

> =======
> Running testOptimizedInterleavePatterns
> Testing SSE optimisation with different interleave patterns (large images) ...
> 0, 0: RGBHalf read as RGBHalf... OK OPTIMISED
> 0, 1: RGBHalf read as RGBAHalf... OK OPTIMISED
> 0, 2: RGBHalf read as ABGRHalf... OK
> 0, 3: RGBHalf read as RGBFloat...
>
> error reading back channel B pixel 72,88 got -nan expected -nan
> Assertion failed: writtenHalf.bits () == readHalf.bits (), file C:\work\BlocksDesign\common\openexr\src\test\OpenEXRTest\testOptimizedInterleavePatterns.cpp, line 268
>

I am testing in Debug mode.
This test passes in 64bit mode.

Run OpenEXRTest in Visual Studio 2022 Debug mode for 32-bit and compare it with the passing 64-bit run. Start with test/OpenEXRTest/testOptimizedInterleavePatterns.cpp at the assertion on line 268 and trace the failing channel comparison. Done means the reported 32-bit failures are resolved while the existing 64-bit behavior still passes.

Written by the indexing model from the issue text.