Add runtime debugging capabilities to OpenGL

The shell property debug.egl.trace can now be set to:

0
  disables tracing
1
  logs all GL calls
error
  checks glGetError after every GL call, logs a stack trace on error
systrace
  logs each GL call to systrace

Change-Id: I34a2a2d4e19c373fd9eaa1b0cd93e67c87378996