Define the namespace for the Affine dialect in ODS (NFC)

This aligns the structure of the Affine dialect on all the other dialects.
In particular this makes the ODS C++ generated code independent of the
enclosing namespace.

mlir/include/mlir/Dialect/Affine/IR/AffineOps.h

@@ -372,12 +372,13 @@ AffineApplyOp makeComposedAffineApply(OpBuilder &b, Location loc, AffineExpr e,
 /// argument.
 void fullyComposeAffineMapAndOperands(AffineMap *map,
                                       SmallVectorImpl<Value> *operands);
-
+} // namespace mlir
 #include "mlir/Dialect/Affine/IR/AffineOpsDialect.h.inc"
 
 #define GET_OP_CLASSES
 #include "mlir/Dialect/Affine/IR/AffineOps.h.inc"
 
+namespace mlir {
 /// Returns true if the provided value is the induction variable of a
 /// AffineForOp.
 bool isForInductionVar(Value val);

mlir/include/mlir/Dialect/Affine/IR/AffineOps.td

@@ -21,7 +21,7 @@ include "mlir/Interfaces/SideEffectInterfaces.td"
 
 def Affine_Dialect : Dialect {
   let name = "affine";
-  let cppNamespace = "";
+  let cppNamespace = "mlir";
   let hasConstantMaterializer = 1;
 }