drmgr_decode_sysnum_from_wrapper () should check for "return 1"

Dr. Memory is hitting an assert caused by drmgr_decode_sysnum_from_wrapper() returning 1 for this function:
```
0:000> U USER32!DdeGetQualityOfService
USER32!DdeGetQualityOfService:
00007ffa`dfadd670 b801000000 mov eax,1
00007ffa`dfadd675 c3 ret
```
Ditto for Set which is the same function:
```
0:000> x user32!Dde*QualityOfService
00007ffa`dfadd670 USER32!DdeSetQualityOfService ()
00007ffa`dfadd670 USER32!DdeGetQualityOfService ()
```

This issue covers changing the decoding function to check for this clearly non-syscall-wrapper case.