[mlir] Use rewriter in linalg Detensorize

[tpopp]

Summary

This is to allow rollbacks on failures of dialect lowering to succeed.

mlir/lib/Dialect/Linalg/Transforms/Detensorize.cpp

matchAndRewrite(GenericOp op, OpAdaptor adaptor,
     Block *originalBlock = op->getBlock();
 
     // Gather some information about the op before inling its region.
     Block *opEntryBlock = &*op.region().begin();
     YieldOp yieldOp = dyn_cast<YieldOp>(op.region().back().getTerminator());
 
     // Split the op's region before the op. This way, we have a clear insertion
     // point in which the op can be inlined.
-    Block *newBlock = originalBlock->splitBlock(op);
+    Block *newBlock = rewriter.splitBlock(originalBlock, Block::iterator(op));
     rewriter.inlineRegionBefore(op.region(), newBlock);
     // Now that op's region is inlined, the operands of its YieldOp are mapped
     // to the materialized target values. Therefore, we can replace the op's
     // uses with those of its YielOp's operands.
     rewriter.replaceOp(op, yieldOp->getOperands());
 
     // No need for these intermediate blocks, merge them into 1.
     rewriter.mergeBlocks(opEntryBlock, originalBlock, adaptor.getOperands());