[mlir:PDLL] Actually run the integration tests

This revealed that the test was a bit out of date and failing, this
commit also tweaks the .mlir to actually test pdll properly.

mlir/test/mlir-pdll/Integration/test-pdll.mlir

@@ -1,17 +1,17 @@
 // RUN: mlir-opt %s -test-pdll-pass | FileCheck %s
 
 // CHECK-LABEL: func @simpleTest
-func @simpleTest() {
+func.func @simpleTest() {
   // CHECK: test.success
   "test.simple"() : () -> ()
   return
 }
 
 // CHECK-LABEL: func @testImportedInterface
-func @testImportedInterface() {
+func.func @testImportedInterface() -> i1 {
   // CHECK: test.non_cast
   // CHECK: test.success
   "test.non_cast"() : () -> ()
-  "builtin.unrealized_conversion_cast"() : () -> (i1)
-  return
+  %value = "builtin.unrealized_conversion_cast"() : () -> (i1)
+  return %value : i1
 }

mlir/test/mlir-pdll/lit.local.cfg

@@ -1,2 +1,2 @@
-config.suffixes = ['.pdll']
+config.suffixes = ['.pdll', '.mlir']
 config.excludes = ['include']