[flang] Fix some memory leaks (#121050)

This commit fixes some but not all memory leaks in Flang. There are
still 91 tests that fail with ASAN.

- Use `mlir::OwningOpRef` instead of `std::unique_ptr`. The latter does
not free allocations of nested blocks.
- Pass `ModuleOp` as value instead of reference.
- Add few missing deallocations in test cases and other places.

1 files changed, 1 insertions, 2 deletions

diff --git a/flang/unittests/Frontend/CodeGenActionTest.cpp b/flang/unittests/Frontend/CodeGenActionTest.cpp
index 5d75de0..e9ff095 100644
--- a/flang/unittests/Frontend/CodeGenActionTest.cpp
+++ b/flang/unittests/Frontend/CodeGenActionTest.cpp
@@ -72,8 +72,7 @@ public:
     mlirCtx->loadDialect<test::DummyDialect>();
 
     mlir::Location loc(mlir::UnknownLoc::get(mlirCtx.get()));
-    mlirModule =
-        std::make_unique<mlir::ModuleOp>(mlir::ModuleOp::create(loc, "mod"));
+    mlirModule = mlir::ModuleOp::create(loc, "mod");
 
     mlir::OpBuilder builder(mlirCtx.get());
     builder.setInsertionPointToStart(&mlirModule->getRegion().front());