EGL: Add EGL_GL_scrgb extension

Test: Android CTS
    adb -d shell am start \
    -n com.drawelements.deqp/android.app.NativeActivity \
    -e cmdLine '"deqp --deqp-case=dEQP-EGL.functional.wide_color.* \
    --deqp-log-filename=/sdcard/dEQP-Log.qpa"'
Bug: 62424735

Change-Id: I12a0bd64c01bcf314b4a73d8eb3151b09bf9f8ae
(cherry picked from commit 33e2b781)