Make fbo completeness format rules forward compatible.

- Detect and expose context version as an extension in glsFBOUtil.
- Add rules for GLES2 formats changed in GLES3 but with no GLES2
  extension with same functionality.
- Add rules for GLES3 formats changed in GLES31 but with no GLES31
  extension with same functionality.

Bug: 18800966
Change-Id: I297fa9738d8e51e87ccf84dfde6a13c7fd45c7ce
5 files changed