Terminal width and height were communicated to the debugger separately,
via SetTerminalWidth() and SetTerminalHeight(). Each notified the
IOHandler and the statusline, so on a resize they recomputed their
layout twice: once with one dimension updated and the other still stale.
Add Debugger::SetTerminalDimensions(width, height) (exposed through
SBDebugger) that updates both properties before notifying, and
reimplement the single-axis setters and the driver's resize handler in
terms of it.
Also fix SBDebugger::GetTerminalHeight(), which returned the width.
Jonas Devlieghere
9aef315020