test verifier

; Using a vmctx global value without declaring it first leads to an error.
function %vmglobal_err(i64) -> i64 {
    gv4 = vmctx ; error: undeclared vmctx reference
ebb0(v0: i64):
    v1 = global_value.i64 gv4
    return v1
}

; If it is declared, all is fine.
function %vmglobal_ok(i64 vmctx) -> i64 {
    gv4 = vmctx
ebb0(v0: i64):
    v1 = global_value.i64 gv4
    return v1
}