[mlir][NFC] Add missing namespace qualifier to ODS generated code

[vinograd47]

Summary

Use ::mlir::Region inside array ref for VariadicRegion.

[rriddle]

Thanks!

mlir/test/mlir-tblgen/op-decl.td

 // CHECK:   ::mlir::Operation::operand_range getODSOperands(unsigned index);
 // CHECK:   ::mlir::Value a();
 // CHECK:   ::mlir::Operation::operand_range b();
 // CHECK:   ::mlir::MutableOperandRange aMutable();
 // CHECK:   ::mlir::MutableOperandRange bMutable();
 // CHECK:   ::mlir::Operation::result_range getODSResults(unsigned index);
 // CHECK:   ::mlir::Value r();
 // CHECK:   ::mlir::Region &someRegion();
-// CHECK:   ::mlir::MutableArrayRef<Region> someRegions();
+// CHECK:   ::mlir::MutableArrayRef<::mlir::Region> someRegions();
 // CHECK:   ::mlir::IntegerAttr attr1Attr()
 // CHECK:   uint32_t attr1();
 // CHECK:   ::mlir::FloatAttr attr2Attr()
 // CHECK:   ::llvm::Optional< ::llvm::APFloat > attr2();
 // CHECK:   ::mlir::Attribute removeAttr2Attr();
 // CHECK:   static void build(::mlir::OpBuilder &odsBuilder, ::mlir::OperationState &odsState, Value val);
 // CHECK:   static void build(::mlir::OpBuilder &odsBuilder, ::mlir::OperationState &odsState, int integer = 0);
 // CHECK:   static void build(::mlir::OpBuilder &odsBuilder, ::mlir::OperationState &odsState, ::mlir::Type r, ::mlir::TypeRange s, ::mlir::Value a, ::mlir::ValueRange b, ::mlir::IntegerAttr attr1, /*optional*/::mlir::FloatAttr attr2, unsigned someRegionsCount)

mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp

void OpEmitter::genNamedRegionGetters() {
   unsigned numRegions = op.getNumRegions();
   for (unsigned i = 0; i < numRegions; ++i) {
     const auto &region = op.getRegion(i);
     if (region.name.empty())
       continue;
 
     // Generate the accessors for a variadic region.
     if (region.isVariadic()) {
-      auto *m = opClass.addMethodAndPrune("::mlir::MutableArrayRef<Region>",
-                                          region.name);
+      auto *m = opClass.addMethodAndPrune(
+          "::mlir::MutableArrayRef<::mlir::Region>", region.name);
       m->body() << formatv("  return (*this)->getRegions().drop_front({0});",
                            i);
       continue;
     }
 
     auto *m = opClass.addMethodAndPrune("::mlir::Region &", region.name);
     m->body() << formatv("  return (*this)->getRegion({0});", i);
   }