[spirv] Make header self-contained. NFC.

diff --git a/mlir/include/mlir/Dialect/SPIRV/Transforms/Passes.h b/mlir/include/mlir/Dialect/SPIRV/Transforms/Passes.h
index 77c5057..ffd589b 100644 (file)
--- a/mlir/include/mlir/Dialect/SPIRV/Transforms/Passes.h
+++ b/mlir/include/mlir/Dialect/SPIRV/Transforms/Passes.h
@@ -16,6 +16,9 @@
 #include "mlir/Pass/Pass.h"
 
 namespace mlir {
+
+class ModuleOp;
+
 namespace spirv {
 
 class ModuleOp;