[BE] Replace M_PI with c10::pi constexpr variable (#50819)
Summary:
Also, get rid of MSVC specific `_USE_MATH_DEFINES`
Test at compile time that c10::pi<double> == M_PI
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50819
Reviewed By: albanD
Differential Revision: D25976330
Pulled By: malfet
fbshipit-source-id: 8f3ddfd58a5aa4bd382da64ad6ecc679706d1284
