Do not emulate EGL 1.5 functionality with extensions

Turns out there are some slight differences between extension
functionality and corresponding core EGL 1.5 functions. They
are not exactly the same, unfortunately and am unable to
pass EGL 1.5 dEQP tests using the cooresponding KHR extensions.

Test: adb -d shell am start -n com.drawelements.deqp/android.app.NativeActivity -e cmdLine '"deqp --deqp-case=dEQP-EGL.functional.reusable_sync* --deqp-log-filename=/sdcard/dEQP-Log.qpa"'
Bug: 129980957
Change-Id: I1ddcc3890d90c6c1a8267591182c9865315cd5cd