[tests] add category for tests that fail under LLVM (#1131)

Context: dotnet/runtime#89190
Context: dotnet/android#8176

Author: jonathanpeppers

tests/Java.Interop-Tests/Java.Interop/JniValueMarshalerContractTests.cs

@@ -399,21 +399,25 @@ public class JniValueMarshaler_Double_ContractTests : JniValueMarshaler_BuiltinT
 }
 
 [TestFixture]
+[Category("LLVMIgnore")]//FIXME: https://github.com/dotnet/runtime/issues/89190
 publicclassJniValueMarshaler_NullableBoolean_ContractTests:JniValueMarshalerContractTests<bool?>{
 protectedoverridebool?Value{get{returntrue;}}
 }
 
 [TestFixture]
+[Category("LLVMIgnore")]//FIXME: https://github.com/dotnet/runtime/issues/89190
 publicclassJniValueMarshaler_NullableSByte_ContractTests:JniValueMarshalerContractTests<sbyte?>{
 protectedoverridesbyte?Value{get{return(sbyte)2;}}
 }
 
 [TestFixture]
+[Category("LLVMIgnore")]//FIXME: https://github.com/dotnet/runtime/issues/89190
 publicclassJniValueMarshaler_NullableChar_ContractTests:JniValueMarshalerContractTests<char?>{
 protectedoverridechar?Value{get{return'3';}}
 }
 
 [TestFixture]
+[Category("LLVMIgnore")]//FIXME: https://github.com/dotnet/runtime/issues/89190
 publicclassJniValueMarshaler_NullableInt16_ContractTests:JniValueMarshalerContractTests<short?>{
 protectedoverrideshort?Value{get{return(short)4;}}
 }