planner: IR only contains function with mocks if functions are mocked

[srenatus]

package test

f = 1

p {
	q with time.now_ns as f
}

q {
	time.now_ns() == 1
}

run with opa build -t plan -e test, we find a plan that contains only one function for q:

            {
                "name": "g0.data.test.q",
                "params": [
                    0,
                    1
                ],
                "return": 2,
                "blocks": [
                    {
                        "stmts": [
                            {
                                "type": "ResetLocalStmt",
                                "stmt": {
                                    "target": 3,
                                    "file": 0,
                                    "col": 1,
                                    "row": 9
                                }
                            },
                            {
                                "type": "CallStmt",
                                "stmt": {
                                    "func": "g0.data.test.f",
                                    "args": [
                                        {
                                            "type": "local",
                                            "value": 0
                                        },
                                        {
                                            "type": "local",
                                            "value": 1
                                        }
                                    ],
                                    "result": 4,
                                    "file": 0,
                                    "col": 3,
                                    "row": 10
                                }
                            },
                            {
                                "type": "AssignVarStmt",
                                "stmt": {
                                    "source": {
                                        "type": "local",
                                        "value": 4
                                    },
                                    "target": 5,
                                    "file": 0,
                                    "col": 3,
                                    "row": 10
                                }
                            },
                            {
                                "type": "MakeNumberRefStmt",
                                "stmt": {
                                    "Index": 2,
                                    "target": 6,
                                    "file": 0,
                                    "col": 3,
                                    "row": 10
                                }
                            },
                            {
                                "type": "EqualStmt",
                                "stmt": {
                                    "a": {
                                        "type": "local",
                                        "value": 5
                                    },
                                    "b": {
                                        "type": "local",
                                        "value": 6
                                    },
                                    "file": 0,
                                    "col": 3,
                                    "row": 10
                                }
                            },
                            {
                                "type": "AssignVarOnceStmt",
                                "stmt": {
                                    "source": {
                                        "type": "bool",
                                        "value": true
                                    },
                                    "target": 3,
                                    "file": 0,
                                    "col": 1,
                                    "row": 9
                                }
                            }
                        ]
                    },
                    {
                        "stmts": [
                            {
                                "type": "IsDefinedStmt",
                                "stmt": {
                                    "source": 3,
                                    "file": 0,
                                    "col": 1,
                                    "row": 9
                                }
                            },
                            {
                                "type": "AssignVarOnceStmt",
                                "stmt": {
                                    "source": {
                                        "type": "local",
                                        "value": 3
                                    },
                                    "target": 2,
                                    "file": 0,
                                    "col": 1,
                                    "row": 9
                                }
                            }
                        ]
                    },
                    {
                        "stmts": [
                            {
                                "type": "ReturnLocalStmt",
                                "stmt": {
                                    "source": 2,
                                    "file": 0,
                                    "col": 1,
                                    "row": 9
                                }
                            }
                        ]
                    }
                ],
                "path": [
                    "g0",
                    "test",
                    "q"
                ]
            },

where we should expect two: one with a call to f, one with the original call to time.now_ns.