[release/6.0] Mono musl support (backport #76500)

[ayakael]

Backport of #76500 to release/6.0

/cc: @am11

Customer Impact

Permits building of mono-flavored runtme on mono-based systems like Alpine Linux. Without this patch, build fails and s390x platforms. This would presumably cover all other mono-supported platforms as well.

Testing

• unit tests in ci
• source-build build within Alpine environment passes

Risk

Low as most of the modifications only expresses themselves when musl-based system is detected.

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Issue Details

---

Backport of #76500 to release/6.0

Customer Impact

Permits building of mono-flavored runtme on mono-based systems like Alpine Linux. Without this patch, build fails and s390x platforms. This would presumably cover all other mono-supported platforms as well.

Testing

• unit tests in ci
• source-build build within Alpine environment passes

Risk

Low as most of the modifications only expresses themselves when musl-based system is detected.

Author:	ayakael
Assignees:	-
Labels:	area-Infrastructure-mono, community-contribution
Milestone:	-

[radical]

WasmBuildTests on this should pass after #78062, which fixes the nuget source for `Microsoft.NET.Workload.Emscripten.Manifest-6.0.400.

[carlossanlop]

WasmBuildTests on this should pass after #78062, which fixes the nuget source for `Microsoft.NET.Workload.Emscripten.Manifest-6.0.400.

This PR touches some native code. This might have to go through Tactics. Do we need this in 7.0.1? Today is the deadline to merge backports that will go into the December release, but the day is almost over to request an approval.

[akoeplinger]

Let's please focus on #76500 first before creating 6.0/7.0 backports. We can do the backports once the main change is in. Closing this in the meantime, thanks 👍