[PM] Rename the CRTP mixin base classes for the new pass manager to

clarify their purpose.

Firstly, call them "...Mixin" types so it is clear that there is no
type hierarchy being formed here. Secondly, use the term 'Info' to
clarify that they aren't adding any interesting *semantics* to the
passes or analyses, just exposing APIs used by the management layer to
get information about the pass or analysis.

Thanks to Manuel for helping pin down the naming confusion here and come
up with effective names to address it.

In case you already have some out-of-tree stuff, the following should be
roughly what you want to update:

  perl -pi -e 's/\b(Pass|Analysis)Base\b/\1InfoMixin/g'

llvm-svn: 263217