JIT: allow pinvoke calli helper in TreatAsShouldHaveRetBufArg

[AndyAyersMS]

If we have multiple cold pinvokes in return positions that return
structs by value and we are merging returns, we will end up querying
these calls post-morph, and may see them using CORINFO_HELP_PINVOKE_CALLI.

Fixes#69612.

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Issue Details

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If we have multiple cold pinvokes in return positions that return
structs by value and we are merging returns, we will end up querying
these calls post-morph, and may see them using CORINFO_HELP_PINVOKE_CALLI.

Fixes #69612.

Author:	AndyAyersMS
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[AndyAyersMS]

@jakobbotsch PTAL
cc @dotnet/jit-contrib

[AndyAyersMS]

3 failures, all unrelated.

• wasm tailcall ([wasm] Stack overflow in JIT/Directed/tailcall/tailcall/tailcall.sh on Linux #69517)
• arm `Assertion failed 'remainingSize == 4' in System.Text.RegularExpressions.Unit.Tests (JIT assert on arm32 when running DllImportGenerator unit tests: remainingSize == 4 #60705)
• LibrariesImportGenerator on arm64 failed with

Assert failure(PID 24 [0x00000018], Thread: 45 [0x002d]): RawGetMethodTable()
File: /__w/1/s/src/coreclr/gc/gc.cpp Line: 4453
Image: /root/helix/work/correlation/dotnet

Similar open issue #68511