Disable function pointer test for crossgen due to a bug (#81286)

Author: fanyang-mono

src/tests/issues.targets

@@ -874,6 +874,9 @@
         <ExcludeList Include="$(XunitTestBinBase)/JIT/opt/ObjectStackAllocation/ObjectStackAllocationTests/*">
             <Issue>https://github.com/dotnet/runtime/issues/81103</Issue>
         </ExcludeList>
+        <ExcludeList Include = "$(XunitTestBinBase)/Loader/classloader/Casting/Functionpointer/**">
+            <Issue>https://github.com/dotnet/runtime/issues/81106</Issue>
+        </ExcludeList>
     </ItemGroup>
 
     <!-- Crossgen2 x86 specific excludes -->