Backport of PR #81122 to .NET 7.0, revert change to issues.targets

Based on tactical discussion with Fan and Sam I have backported
the PR #81122 including the removal of the issues.targets entry
for function pointer tests as an extra commit on top of
the backport of Fan's PR #80855.

Thanks

Tomas

Author: trylek

src/coreclr/tools/Common/Compiler/NativeAotNameMangler.cs

@@ -303,9 +303,8 @@ private string ComputeMangledTypeName(TypeDesc type)
                     mangledName = GetMangledTypeName(((PointerType)type).ParameterType) + NestMangledName("Pointer");
                     break;
                 case TypeFlags.FunctionPointer:
-                    // TODO: need to also encode calling convention (or all modopts?)
                     var fnPtrType = (FunctionPointerType)type;
-                    mangledName = "__FnPtr" + EnterNameScopeSequence;
+                    mangledName = "__FnPtr_" + ((int)fnPtrType.Signature.Flags).ToString("X2") + EnterNameScopeSequence;
                     mangledName += GetMangledTypeName(fnPtrType.Signature.ReturnType);
 
                     mangledName += EnterNameScopeSequence;

src/tests/issues.targets

@@ -919,9 +919,6 @@
         <ExcludeList Include="$(XunitTestBinBase)/JIT/jit64/opt/cse/hugeexpr1/*">
             <Issue>https://github.com/dotnet/runtime/issues/62881</Issue>
         </ExcludeList>
-        <ExcludeList Include = "$(XunitTestBinBase)/Loader/classloader/Casting/Functionpointer/**">
-            <Issue>https://github.com/dotnet/runtime/issues/81106</Issue>
-        </ExcludeList>
     </ItemGroup>
 
     <!-- All OSX targets on NativeAOT -->