mdb save-args matching should only consider insns which have executed
At present, we search for the save-args prologue within 80 bytes of the start of the function, regardless of the position of %pc. This leads us to possibly match a function, and return its "arguments" when the actual saving of arguments has not yet occurred.
We should limit our search to the current function prior to the program counter.
This may backfire if the function were to have a backward branch or jump from after argument saving to a place before it, but this is both unlikely and, were it to happen, grossly damaging to the whole concept of the save area in general.