I applied your mod manually to the original sph-sgminer I have checkout on my xubuntu mining rig and it's working properly with MPOS based pools that was previously rejecting my shares with quarkcoin kernel or with qubitcoin kernel. Thanks a lot !
sgminer 4.1.0-85-gccc7d-dirty - Started: [2014-03-16 00:24:30]
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(5s):19.60M (avg):19.56Mh/s | A:137 R:1 HW:0 WU:0.273/m
ST: 3 SS: 1 NB: 1040 LW: 74215 GF: 1 RF: 0
Connected to Pool 0 (stratum) diff 0.049 as user youllneverknow.1
Block: 1e64fda1... Diff:1.56K Started: [08:48:53] Best share: 114
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[P]ool management [G]PU management [S]ettings [D]isplay options [Q]uit
GPU 0: 71.0C 1474RPM | 4.901M/4.892Mh/s | R: 1.1% HW:0 WU:0.068/m I:13
GPU 1: 65.0C 1433RPM | 4.904M/4.892Mh/s | R: 0.5% HW:0 WU:0.068/m I:13
GPU 2: 62.0C 1490RPM | 4.886M/4.889Mh/s | R: 0.7% HW:0 WU:0.068/m I:13
GPU 3: 67.0C 1463RPM | 4.903M/4.890Mh/s | R: 1.0% HW:0 WU:0.068/m I:13
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[08:47:35] Pool 0 difficulty changed to 0.020
[08:47:35] Accepted 70190c1a Diff 0.009/0.004 GPU 2
[08:47:35] Accepted a36d2938 Diff 0.006/0.004 GPU 1
[08:47:35] Accepted e38978dd Diff 0.004/0.004 GPU 0
[08:47:35] Accepted c054be49 Diff 0.005/0.004 GPU 0
[08:47:35] Accepted 52397311 Diff 0.012/0.004 GPU 1
[08:47:35] Accepted 4d1ef28a Diff 0.013/0.004 GPU 0
[08:47:35] Accepted 2058fdcd Diff 0.031/0.004 GPU 1
[08:47:37] Accepted 25deddb0 Diff 0.026/0.020 GPU 3
[08:47:38] Accepted 11cc842d Diff 0.056/0.020 GPU 2
[08:47:38] Accepted 07001512 Diff 0.143/0.020 GPU 0
[08:47:44] Accepted 1a4588a9 Diff 0.038/0.020 GPU 0
[08:47:49] Accepted 32017447 Diff 0.020/0.020 GPU 0