DEFINE_DISPATCH in the correct namespace. (#30308)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30308
Dispatch is declared in non-anonymous namespace, so it definitely
shouldn't be defined in an anonymous namespace. This doesn't seem
to matter today, but it matters when we split libtorch into two
libraries.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Differential Revision: D18762361
Pulled By: ezyang
fbshipit-source-id: 484f0fab183c385dd889db9dad3e48e92e0a3900
