vcldemo: render more small scaled page-border alikes

Change-Id: I2605175e7ee66d3da5e41497baa4178074830e99
vcl: since we share Bitmaps across all GLContexts simplify lifecycle.

~X11SalVirtualDevice() was destroying X resources referred to by
OpenGLSalBitmap's mpContext, which were subsequently accessed by
Bitmap::AcquireReadAccess on the floating Bitmap. Better to use the
default window's GLContext for all bitmap operations.

Change-Id: I9009980e791cff1a1f36d626592d72c7a32efd39
vcl: fix un-initialized log length & clean copy/paste bits.

Change-Id: I39cd9ef32fafa2894ffde961d87adc6aac9d4a4f