[MLIR][NFC] Fix incomplete boundary comments. (#133516)

I observed that we have the boundary comments in the codebase like:

```
//===----------------------------------------------------------------------===//
// ...
//===----------------------------------------------------------------------===//
```

I also observed that there are incomplete boundary comments. The
revision is generated by a script that completes the boundary comments.

```
//===----------------------------------------------------------------------===//
// ...

...
```

Signed-off-by: hanhanW <[email protected]>

Author: hanhanW

mlir/include/mlir-c/Rewrite.h

@@ -48,6 +48,7 @@ mlirRewriterBaseGetContext(MlirRewriterBase rewriter);
 
 //===----------------------------------------------------------------------===//
 /// Insertion points methods
+//===----------------------------------------------------------------------===//
 
 // These do not include functions using Block::iterator or Region::iterator, as
 // they are not exposed by the C API yet. Similarly for methods using
@@ -101,6 +102,7 @@ mlirRewriterBaseGetBlock(MlirRewriterBase rewriter);
 
 //===----------------------------------------------------------------------===//
 /// Block and operation creation/insertion/cloning
+//===----------------------------------------------------------------------===//
 
 // These functions do not include the IRMapper, as it is not yet exposed by the
 // C API.

mlir/lib/CAPI/Transforms/Rewrite.cpp

@@ -29,6 +29,7 @@ MlirContext mlirRewriterBaseGetContext(MlirRewriterBase rewriter) {
 
 //===----------------------------------------------------------------------===//
 /// Insertion points methods
+//===----------------------------------------------------------------------===//
 
 void mlirRewriterBaseClearInsertionPoint(MlirRewriterBase rewriter) {
   unwrap(rewriter)->clearInsertionPoint();
@@ -69,6 +70,7 @@ MlirBlock mlirRewriterBaseGetBlock(MlirRewriterBase rewriter) {
 
 //===----------------------------------------------------------------------===//
 /// Block and operation creation/insertion/cloning
+//===----------------------------------------------------------------------===//
 
 MlirBlock mlirRewriterBaseCreateBlockBefore(MlirRewriterBase rewriter,
                                             MlirBlock insertBefore,