[gcov] Simplify cc1 options and remove CodeGenOptions EmitCovNotes/EmitCovArcs

[gcov] Simplify cc1 options and remove CodeGenOptions EmitCovNotes/EmitCovArcs

After a07b135ce0c0111bd83450b5dc29ef0381cdbc39, we always pass
-coverage-notes-file/-coverage-data-file for driver options
-ftest-coverage/-fprofile-arcs/--coverage. As a bonus, we can make the following
simplification to cc1 options:

* `-ftest-coverage -coverage-notes-file a.gcno` => `-coverage-notes-file a.gcno`
* `-fprofile-arcs -coverage-data-file a.gcda` => `-coverage-data-file a.gcda`

and remove EmitCovNotes/EmitCovArcs.