Fix native type for data types I4 and U4 (to match native declarations) (#91)

***UPDATE_DEPENDENTS***

Author: josesimoes

source/MetadataProcessor.Core/Extensions/TypeReferenceExtensions.cs

@@ -113,9 +113,9 @@ public static string ToNativeTypeAsString(this TypeReference type)
                     case nanoCLR_DataType.DATATYPE_U2:
                         return "uint16_t";
                     case nanoCLR_DataType.DATATYPE_I4:
-                        return "int32_t";
+                        return "signed int";
                     case nanoCLR_DataType.DATATYPE_U4:
-                        return "uint32_t";
+                        return "unsigned int";
                     case nanoCLR_DataType.DATATYPE_I8:
                         return "int64_t";
                     case nanoCLR_DataType.DATATYPE_U8: