use a gradient pattern in the framebuffer

Change-Id: I7dd453796c285d9f319997c2f567b42e3b4307b7
moved gralloc/testhdmidisplay.cpp to example/hdmidisplay

Change-Id: Ie7a0d91746e7b0e2c9a21112c32fd329c8a47ef1
fixed typo: pinx->pinx

Change-Id: I43f2f4f040f8fcb2f8ec31b19104da9d0ce8643d