emulator: allows surfaceflinger to change qemu.gles value

This is to allow surfaceflinger to always load vendor provided
egl libraries first and fall back to software renderer, and then
set the qemu.gles to correct value reflecting what libraries
are actually used.

bug: 27273457

Change-Id: Ifaca31aa2e562f50baa41fd228df9836bc3b1667
1 file changed