monitor_reconfigure: Try to improve resolution selection.

My initial thinking was that this should work as follows:
- find the device with the lowest max resolution
- set the other device to use the nearest resolution that
  it has to the first's (that's >= it)
- set the screen to use the first, smaller device's
  resolution (with black bars taking up the extra space
  on the larger device)

xrandr doesn't appear to let the screen be a lower resolution
than any of the devices, though.  Regardless, I tried this
version with a low-res Eee, a high-res Eee, and an X200, on
both a projector and on a VC device, and it did something
reasonable on all of them, so it seems like it's probably
worth checking it in soon to make Kan happy and then refining
it further. :-)

TEST=tried it on an X200 and various Eee PCs with a few projectors

Review URL:
2 files changed
tree: 24bfdfff6ec4807de98b4485c1d629f71336802b
  1. Makefile
  4. monitor_reconfigure_main.h