Disabled LTO for x86 clang-cl CI builds

[mihe]

This solution is not ideal, but I keep seeing x86 clang-cl builds failing from what looks like it being out of memory.

This stems from Visual Studio only shipping two editions of LLVM, one for x86 and for x64, instead of the four editions it ships of Visual C++, where you have one pair for each host architecture. This means that x86 clang-cl builds are currently being compiled with a 32-bit compiler/linker, which seem to hit their memory ceiling at random times.

LTO has historically been a real memory hog, so I'm hoping this will give me some breathing room until I can fix this in some other way.

The proper solution will most likely be to make a CMake toolchain file for clang-cl on Windows, which should let me bypass CMake's scanning of output binaries and effectively cross-compile x86-on-x64. This would also let us use the official release of LLVM, instead of having to rely on the (seemingly custom) Microsoft-provided one, which should help shorten scripts/ci_setup_windows.ps1 a fair bit.

[mihe]

With no option to disable LTO/LTCG in Jolt itself, I'm realizing that this workaround might not be viable. I should just go for the toolchain file instead.

[mihe]

I ended up creating a pull request (jrouwe/JoltPhysics#357) for Jolt to add an option for disabling LTO, so this PR was able to go forward after all.

I limited it to only x86 clang-cl builds instead of all builds. We'll see how this goes.