Namespace cleanup for 1.7 Part 2 (#46673)
Summary:
make valgrind_toggle and valgrind_supported_platform private functions
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46673
Reviewed By: gchanan
Differential Revision: D24458133
Pulled By: albanD
fbshipit-source-id: 6f3fad9931d73223085edbd3cd3b7830c569570c
