Summary:
This renames `WindowsTorchApiMacro.h` to `Export.h` to mirror the c10 header `c10/macros/Export.h` and also updates it to use `C10_EXPORT`/`C10_IMPORT`. This also removes the `THP_API` macro from `THP_export.h` which appears to serve the same purpose.
cc pietern mrshenli pritamdamania87 zhaojuanmao satgera rohan-varma gqchen aazzolini osalpekar jiayisuse SciPioneer H-Huang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68095
Reviewed By: jbschlosser
Differential Revision: D32810881
Pulled By: albanD
fbshipit-source-id: d6949ccd0d80d6c3e5ec1264207611fcfe2503e3
