Change code coverage option name (#43999)
Summary:
According to [documentation](https://github.com/pytorch/pytorch/blob/master/tools/setup_helpers/cmake.py#L265), only options starts with `BUILD_` / `USE_` / `CMAKE_` in `CMakeLists.txt` can be imported by environment variables.
---
This diff is originally intended to enable `c++` source coverage with `CircleCI` and `codecov.io`, but we will finish it in the future. You can find the related information in the diff history. Following is the originally procedur:
Based on [this pull request](https://github.com/pytorch/pytorch/commit/1bda5e480c0fe01dae8db718cd457befa1b46ac6), life becomes much easier for this time.
1.in `build.sh`
- Enable coverage builld option for c++
- `apt-get install lcov`
2.in `test.sh`
- run `lcov`
3.in `pytorch-job-specs.yml`
- copy coverage.info to `test/` folder and upload it to codecov.io
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43999
Test Plan: Test on github
Reviewed By: malfet
Differential Revision: D23464656
Pulled By: scintiller
fbshipit-source-id: b2365691f04681d25ba5c00293fbcafe8e8e0745
