Patch to make IronPython build for .NET 2.0

ipyclr2.patch

diff --git a/Languages/IronPython/IronPython.Modules/_csv.cs b/Languages/IronPython/IronPython.Modules/_csv.cs
index 982a735..9eef957 100644
--- a/Languages/IronPython/IronPython.Modules/_csv.cs
+++ b/Languages/IronPython/IronPython.Modules/_csv.cs
@@ -739,7 +739,11 @@ in CSV format.")]
                     _state = State.StartRecord;
                     _fields.Clear();
                     _is_numeric_field = false;
+#if !CLR2
                     _field.Clear();
+#else
+                    _field = new StringBuilder();
+#endif
                 }
 
                 #endregion
@@ -982,7 +986,11 @@ in CSV format.")]
                     else
                         _fields.Add(field);
 
+#if !CLR2
                     _field.Clear();
+#else
+                    _field = new StringBuilder();
+#endif
                 }
             }
 
diff --git a/Languages/IronPython/IronPython/Modules/_ast.cs b/Languages/IronPython/IronPython/Modules/_ast.cs
index f486239..935649d 100644
--- a/Languages/IronPython/IronPython/Modules/_ast.cs
+++ b/Languages/IronPython/IronPython/Modules/_ast.cs
@@ -301,7 +301,11 @@ namespace IronPython.Modules
                 if (expr.Value == null)
                     return new Name("None", Load.Instance);
 
-                if (expr.Value is int || expr.Value is double || expr.Value is Int64 || expr.Value is BigInteger || expr.Value is Complex)
+                if (expr.Value is int || expr.Value is double || expr.Value is Int64 || expr.Value is BigInteger 
+#if !CLR2
+                        || expr.Value is Complex
+#endif
+                        )
                     ast = new Num(expr.Value);
                 else if (expr.Value is string)
                     ast = new Str((string)expr.Value);