LLVM optimised math: Ensure build ifdefs exactly match Elements and EBuild

[davidm-ro]

The build error: https://remobjects.slack.com/archives/C0250BVCW/p1764517386554229

Build for 20251130-152429-elements-develop failed. Error Action: script | function compile | function compileIsland | function runEBuild | ebuild.runCustomEBuild | ebuild(Source/IslandRTL/Source/Island.sln --debug "--setting:IslandSDKFolder=c:\CI\b\elements\937\Island\SD...): 'Error: E: Duplicate method "class method Acos(d: Double): Double" with same signature [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.PurePascal.pas (20)]'.

This seems to be macOS:

Source file: c:\CI\b\elements\937\Source\IslandRTL\Source\VersionHelpers.pas
Reference: c:\CI\b\elements\937\Island\GC\Darwin\macOS\x86_64\gc.fx
Reference: c:\CI\b\elements\937\Island\SDKs\Darwin\macOS 26.0\CoreFoundation.fx
Reference: c:\CI\b\elements\937\Island\SDKs\Darwin\macOS 26.0\Foundation.fx
Reference: c:\CI\b\elements\937\Island\SDKs\Darwin\macOS 26.0\rtl.fx
-> Phase Resolving Bodies, Device-x86_64 started.
E: Duplicate method "class method Acos(d: Double): Double" with same signature [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.PurePascal.pas (20)]
N: Previous declaration was here [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.LLVMVectorLib.pas (79)]
E: Duplicate method "class method Asin(d: Double): Double" with same signature [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.PurePascal.pas (21)]
N: Previous declaration was here [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.LLVMVectorLib.pas (81)]
E: Duplicate method "class method Atan(d: Double): Double" with same signature [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.PurePascal.pas (22)]
N: Previous declaration was here [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.LLVMVectorLib.pas (83)]
E: Duplicate method "class method Atan2(x: Double; y: Double): Double" with same signature [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.PurePascal.pas (23)]
N: Previous declaration was here [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.LLVMVectorLib.pas (85)]
E: Duplicate method "class method Ceiling(d: Double): Double" with same signature [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.PurePascal.pas (24)]
N: Previous declaration was here [c:\CI\b\elements\937\Source\IslandRTL\Source\Math.LLVMVectorLib.pas (87)]

But how? I simplified the version conditionals, which had grown as I had picked and excluded some CPU architectured. I am not confident this solves it; I'm really puzzled.