🚀 Feature

Support a Bazel build of pytorch, equal in capacity to the cmake build

Motivation

pytorch integration with bazel projects is substantially easier with a bazel ruleset and target surface. Additional uses include from-source build capacity, with unique global configurations like sanitizers.

Pitch

bazel building and testing with clear instructions for using pytorch as an external repository without patches, direct from release/git commit.

Alternatives

Using binary-only releases and rules_foreign_cc

Additional context

This is currently in use at Uber ATG, where a successful build and test of cpu and gpu (nvcc) targets occurs on a daily basis. The changes required for this will be adapted, improved, and released as the starting point. Further work should be detailed in additional tasks.