Make sure clear_conditionsets feeds in 1 to MAXCONDITIONSETS instead of 0 to...

Make sure clear_conditionsets feeds in 1 to MAXCONDITIONSETS instead of 0 to MAXCONDITIONSETS-1, so that M_ClearConditionSet can use them all properly AND clear all condition sets properly.

Apparently the mistake also caused myargc to be cleared in Linux64 SDL2 (as pointed out by that ilag11111 guy on GitHub), so that should be fixed now too.