[coroutines] Call initializePass in coroutine pass constructors

Summary:

Fixes: https://bugs.llvm.org/show_bug.cgi?id=33226

Reviewers: chandlerc, davide, majnemer, dblaikie

Reviewed By: chandlerc

Subscribers: EricWF, llvm-commits

Differential Revision: https://reviews.llvm.org/D33701

llvm-svn: 304277