GDI related memory leak

[GoogleCodeExporter]

When continually toggling GDI+ mode on and off with the emulator running, 
memory usage will slowly rise.  Much more easily seen in r3307 or earlier in 
MainForm.CaptureOSD(), which can easily hit the 2G limit in a short amount of 
time doing video capture.

As best as I can tell, if you instantiate a SysdrawingRenderPanel, render to it 
at least once, and then get rid of it, it leaks.  I couldn't say for sure, 
though.

Original issue reported on code.google.com by [email protected] on 2 Oct 2012 at 9:31