qcommon: never sleep with common.framerate.max -2

src/engine/qcommon/common.cpp

@@ -907,11 +907,10 @@ void Com_Frame()
  max = maxfps.Get();
  }
 
- // A positive maxfps caps the fps to the given number, with an implicit
- // cap at 333fps to avoid bugs. Above 333fps minMsec is less than 3.
- // At 1 or 2 minMsec, the game still runs but exhibits various issues
- // such as first-person weapon model flickering, or client having
- // connection issues with server.
+ /* A positive maxfps caps the fps to the given number, with an implicit
+ cap at 333fps to avoid bugs. Above 333fps minMsec is less than 3 and with
+ minMsec being 2 or less some variables may become zero and some code may
+ experience division by zero. */
  if ( max > 0 )
  {
  minMsec = std::max( 1000 / max, 3 );
@@ -921,11 +920,17 @@ void Com_Frame()
  {
  minMsec = 3;
  }
- // A negative maxfps really unlocks fps (and bugs).
- else
+ /* A negative maxfps unlocks fps more (and unfortunate bugs) but cap
+ it to 1000 (because of a remaining sleep it's a bit less than that). */
+ else if ( max == -1 )
  {
  minMsec = 1;
  }
+ // A maxfps smaller than -1 unlocks all remaining fps (and expected bugs). 
+ else
+ {
+ minMsec = 0;
+ }
  }
  }
  else