pixelflinger: Provide more scanline shortcut functions.

This patch adds a dozen more "shortcut" scanline-processing functions
to pixel-flingers. All of them avoid using the JIT for the corresponding
operation (on ARM), or using the generic and _extremely_ slow 'scanline'
function (on x86, where there is no JIT).

The shortcuts were selected by running the system under emulation
(build full_x86-eng, then launch emulator-x86), and correspond to
operations that are in use when using the system's typical UI features.

This makes it much more responsive and amenable to testing most
applications, at least those that don't use OpenGL ES heavily.

Note that HW OpenGLES emulation is under completion and should solve this
problem entirely, though is not there yet.

Change-Id: I9c73ba21ad158d6cc5532fabe7ed2419e00ecb3f