Update pencil-util submodule

Change-Id: I1078e095e42a58b2b742848506960d17ea656121
Support C-like built-in function.

Change-Id: I57206d4af97ea57e22c1aee0f9e909966531af89
Remove function calls without side effects.

Change-Id: I6e7a0fda8ea9e53d90f2b250e8e7988dcc577b24