[MichalStrehovsky]

Wasm was running into linker warnings (visible in our first CI results!):

##[warning]wasm-ld(0,0): warning : function signature mismatch: sin [/__w/1/s/src/tests/nativeaot/nativeaot.csproj]
    >>> defined as (i32, f64) -> f64 in /__w/1/s/artifacts/tests/coreclr/obj/wasi.wasm.Checked/Managed/nativeaot/nativeaot/native/nativeaot.o
    >>> defined as (f64) -> f64 in /__w/1/s/.dotnet/wasm-tools/wasi-sdk/34.0-linux-x64//share/wasi-sysroot/lib/wasm32-wasip2/libc.a(sin.c.obj)

Route x86 and WASM math calls through distinct runtime wrappers, including floating-point remainder helpers, while preserving direct libc imports on other architectures.

x86 used some /alternatename linker tricks to keep the names as their C library function, but I don't think it's possible on WASM because WASM doesn't do the x86 Windows symbol name manglings and sin is sin.

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[Copilot]

🔵 Needs a closer look

Cross-architecture calling-convention changes need x86 and WASM link-and-run validation, which was not performed during this review.

No open issues 🎉

What changed in this PR

Fixes NativeAOT math calling-convention mismatches by routing x86 and WASM calls through dedicated runtime wrappers.

Changes:

• Renames math wrappers with the Rhp prefix and enables them for WASM.
• Updates managed imports and remainder helper mappings while preserving direct libc calls on other architectures.

File	Description
src/​coreclr/​tools/​aot/​ILCompiler.Compiler/​Compiler/​DependencyAnalysis/​KnownExternFunctions.cs	Routes x86/WASM remainder helpers through wrappers.
src/​coreclr/​nativeaot/​System.Private.CoreLib/​src/​System/​Runtime/​RuntimeImports.cs	Selects architecture-specific math imports.
src/​coreclr/​nativeaot/​Runtime/​MathHelpers.cpp	Renames wrappers and enables WASM support.

_{Review effort: Balanced}

[MichalStrehovsky]

/azp run runtime-nativeaot-outerloop

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