Removing -ddump-simpl-phases and -ddump-core-pipeline flags?

[Jan Stolarek]

As part of #9358 I'm considering removing these two flags:

-ddump-simpl-phases: dumps simplifier statistics for phases of the simplifier but it works only 
when used together with -ddump-simpl-stats. User can limit which statistics are displayed by 
passing in either the simplifier phase number (0,1,2), phase name (final, main, 
post-worker-wrapper, Gentle) or both (separated with ":"). So for 
example -ddump-simpl-phases=0:main,1 dumps statistics for all pases labeled as phase 1 and only 
those pases of phase 0 that are named "main". Has anyone ever used that flag? Do we consider it 
useful?

-ddump-core-pipeline: this seems like a partially implemented stub. The name is very misleading 
because it is related to plugins. The only thing that it seems to do at the moment is that 
when -ddump-to-file is set then -ddump-core-pipeline will result in dumping plugin passes to 
file.

Janek