Fix link of libmlir.so by adding ExecutionEngine as dependency to GPUTransforms

This feels like a layering violation, but it fixes the build.

Fixes #54242

tools/mlir/lib/Dialect/GPU/CMakeFiles/obj.MLIRGPUTransforms.dir/Transforms/SerializeToHsaco.cpp.o:SerializeToHsaco.cpp:function (anonymous namespace)::SerializeToHsacoPass::optimizeLlvm(llvm::Module&, llvm::TargetMachine&):
error: undefined reference to 'mlir::makeOptimizingTransformer(unsigned int, unsigned int, llvm::TargetMachine*)'