crossgen2 ARM support misc (#21109)

Author: y-yamshchikov

src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/ReadyToRunMetadataFieldLayoutAlgorithm.cs

@@ -104,6 +104,11 @@ private class ModuleFieldLayoutMap : LockFreeReaderHashtable<EcmaModule, ModuleF
             /// </summary>
             private const int DomainLocalModuleNormalDynamicEntryOffsetOfDataBlobArm64 = 8;
 
+            /// <summary>
+            /// CoreCLR DomainLocalModule::NormalDynamicEntry::OffsetOfDataBlob for Arm
+            /// </summary>
+            private const int DomainLocalModuleNormalDynamicEntryOffsetOfDataBlobArm = 4;
+
             protected override bool CompareKeyToValue(EcmaModule key, ModuleFieldLayout value)
             {
                 return key == value.Module;
@@ -398,6 +403,10 @@ public FieldAndOffset[] GetOrAddDynamicLayout(DefType defType, ModuleFieldLayout
                             nonGcOffset = DomainLocalModuleNormalDynamicEntryOffsetOfDataBlobArm64;
                             break;
 
+                        case TargetArchitecture.ARM:
+                            nonGcOffset = DomainLocalModuleNormalDynamicEntryOffsetOfDataBlobArm;
+                            break;
+
                         default:
                             throw new NotImplementedException();
                     }

src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/ObjectWriter/TargetExtensions.cs

@@ -42,6 +42,9 @@ public static Machine MachineFromTarget(this TargetDetails target)
                 case Internal.TypeSystem.TargetArchitecture.ARM64:
                     return Machine.Arm64;
 
+                case Internal.TypeSystem.TargetArchitecture.ARM:
+                    return Machine.ArmThumb2;
+
                 default:
                     throw new NotImplementedException(target.Architecture.ToString());
             }