[mlir] Correct 2 places that result in corrupted conversion rollbacks

This corrects the last 2 issues caught by tests when causing dialect
conversion rollbacks to occur.

Differential Revision: https://reviews.llvm.org/D94623

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

@@ -2144,7 +2144,7 @@ Value mlir::LLVM::createGlobalString(Location loc, OpBuilder &builder,
   assert(module && "builder points to an op outside of a module");
 
   // Create the global at the entry of the module.
-  OpBuilder moduleBuilder(module.getBodyRegion());
+  OpBuilder moduleBuilder(module.getBodyRegion(), builder.getListener());
   MLIRContext *ctx = builder.getContext();
   auto type = LLVM::LLVMArrayType::get(IntegerType::get(ctx, 8), value.size());
   auto global = moduleBuilder.create<LLVM::GlobalOp>(

mlir/lib/Transforms/Utils/DialectConversion.cpp

@@ -849,6 +849,7 @@ static void detachNestedAndErase(Operation *op) {
       block.dropAllDefinedValueUses();
     }
   }
+  op->dropAllUses();
   op->erase();
 }