libEGL: Add initialization tracing

The first call to eglGetDisplay() loads drivers and initializes
dispatch tables. This currently takes significant time (85-100 ms),
and can must be done before the first frame of an app can be shown.

This change adds systrace markers for the major parts of this process,
as a precursor to optimizing them.

Bug: 34404021
Test: manual systrace of calculator app startup on bullhead
Change-Id: If1ecb5a81f9d33daf72c6f3e5b403972f8529b2d