rasapi32: RasEnumConnections now returns correct buffer size (zero) when there are zero connections available.

gdi32: Make sure that we don't read/write beyond the provided buffer in GetOutlineTextMetricsA, add a test case.

user32: Although Windows sends WM_GETMINMAXINFO at the window creation time, it doesn't use returned values to set window size.

Should fix Coverity CID-348 (dereference before NULL check).