Undo: Fix state entry bug for parallel state groups

This commit reverts c4cef6fae9f2a55f21fc9517855dfcf659c89081.
The above fix for QTBUG-25958 (cloned in QTBUG-40219) is not
complete and introduces the regression QTBUG-30049.

Task-number: QTBUG-30049, QTBUG-25958, QTBUG-40219
Change-Id: I3c4b774dce06c13cb4e089f8413a7747cedfd212
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Doc: Placed Qt OpenGL class convention in code block.

-QDoc tried to autolink where it should not.
-The syntax looks much better in a code block than in a paragraph.

Change-Id: I21d08cbb1537186d09b52898d7b70a5c0794256c
Task-number: QTBUG-35019
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>