renderthread: add EGL_EXT_buffer_age support

EGL_EXT_buffer_age is better than EGL_BUFFER_PRESERVED
because it can save memory bandwidth used to blit
back buffer into front buffer.

Change-Id: I2fea0ee08dc7dd66e348b04dd694d075d509d01b
(cherry picked from commit 13d1b4ab10fbee5e81a2ba1ac59cfae1e51d3ef0)
7 files changed