VulkanContext: Disable subgroup reduction on Macs with AMD GPUs

[OatmealDome]

Based on #9783.

For whatever reason, attempting to access gl_SubgroupInvocationID causes MTLCompilerService to crash in LLVM code. This breaks bounding box. A crash log has been attached here.

The relevant excerpt is as follows:

Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:       KERN_INVALID_ADDRESS at 0x00007fffb1d44a50
Exception Note:        EXC_CORPSE_NOTIFY

[...]

Thread 1 Crashed:
0   ???                           	0x00007fffb1d44a50 0 + 140736176867920
1   libLLVM.dylib                 	0x00007fff68d6ddf9 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) + 1573
2   libLLVM.dylib                 	0x00007fff68d6cfd1 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) + 1633
3   libLLVM.dylib                 	0x00007fff68797d65 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) + 119
4   libLLVM.dylib                 	0x00007fff68919ff5 llvm::FPPassManager::runOnFunction(llvm::Function&) + 395
5   libLLVM.dylib                 	0x00007fff68919d56 llvm::FPPassManager::runOnModule(llvm::Module&) + 52
6   libLLVM.dylib                 	0x00007fff6891fa2e llvm::legacy::PassManagerImpl::run(llvm::Module&) + 652
7   com.apple.AMDRadeonX6000Shared	0x00007fff60bf79f5 AMDMTLCompilerPluginIL::compileShader(llvm::Module&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >&) + 639

More investigation is required and a bug report with a minimized test case should be submitted to Apple.

In the meantime, however, I have opened this PR which disables subgroup reduction completely on AMD GPUs so that games that rely on bounding box can become playable again.

Tested on a MacBook Pro 16" running macOS 11.5.2 with an AMD Radeon 5500M.

[Techjar]

Neat. Glad you found the issue.

[Techjar]

Code LGTM (I'm basically the one who wrote it :P), probably should try to find out if this is a problem on newer iMac Pros with AMD Vega graphics.