#1436 Shift reset time too short for 6581

[Leandro Nini]

It seems that the shift register reset time for the 6581 is too short causing the failure of two tests:

SID/resid-test/oscsample0-6581
SID/resid-test/oscsample1-6581

Attached a dump of the noise waveform from x64sc with the current code, were it appears that the register is being reset too often during sampling.

Increasing the SHIFT_REGISTER_RESET_START_6581 in src/resid/wave.cc to something like 35000 make the tests pass.

There is no mention about which chip was used for sampling in the test, maybe it was an R4 with longer reset times?

[gpz]

Those tests are really VERY old... so probably noone knows :)

I usually check against my Breadbox that contains a SID with the Marking: MOS / 6581 / 2084

[gpz]

patch applied in r43784, thanks!