Make CompilationUnit own Functions (#22202)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22202
ghimport-source-id: de6c963af1df76d2d6357155e64a5913ab879f76
Test Plan: Imported from OSS
Differential Revision: D15998761
Pulled By: suo
fbshipit-source-id: 5414a6424953738d823b265d20dc67dde6e5b2d8
