Tracking integration of AVX2 ChaCha20 from hacl-star. We already have AVX and non-vectorized versions, but we should also leverage the AVX2 implementation.

• HACL* : Import AVX2 code for Chacha20, Poly1305 and CP
• HACL* : Special code modifications to avoid generating unused variables
• NSS : New flag NSS_DISABLE_AVX2 for freebl/Makefile and freebl.gyp
• NSS : Disable use of AVX2 on GCC 4.4 which doesn’t support -mavx2

Once properly reviewed and updated, merge will need to wait on my upstream changes to HACL* and Kremlin.

Fixed upstream and merged in master: https://github.com/project-everest/hacl-star/issues/232

Depends on D62606

Depends on D63829

https://hg.mozilla.org/projects/nss/rev/d5deac55f54350d60fd6ae69899ac399fdfcfc72

Windows build failures on uplift try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=0ec871448bebfb523ba45df47fc6259e25ecc1ae&selectedJob=291328468

lld-link: error: undefined symbol: Hacl_Impl_Poly1305_Field32xN_128_load_acc2
[task 2020-03-02T21:45:00.109Z] 21:45:00     INFO -  >>> referenced by Z:\task_1583182070\build\src\security\nss\lib\freebl\verified\Hacl_Chacha20Poly1305_128.c:41
[task 2020-03-02T21:45:00.109Z] 21:45:00     INFO -  >>>               ..\freebl_hw-acc-crypto-avx\Hacl_Chacha20Poly1305_128.obj:(poly1305_padded_128)
[task 2020-03-02T21:45:00.109Z] 21:45:00     INFO -  lld-link: error: undefined symbol: Hacl_Impl_Poly1305_Field32xN_128_fmul_r2_normalize
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  >>> referenced by Z:\task_1583182070\build\src\security\nss\lib\freebl\verified\Hacl_Chacha20Poly1305_128.c:263
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  >>>               ..\freebl_hw-acc-crypto-avx\Hacl_Chacha20Poly1305_128.obj:(poly1305_padded_128)
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  lld-link: error: undefined symbol: Hacl_Impl_Poly1305_Field32xN_256_load_acc4
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  >>> referenced by Z:\task_1583182070\build\src\security\nss\lib\freebl\verified\Hacl_Chacha20Poly1305_256.c:41
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  >>>               ..\freebl_hw-acc-crypto-avx2\Hacl_Chacha20Poly1305_256.obj:(poly1305_padded_256)
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  Z:/task_1583182070/build/src/config/rules.mk:608: recipe for target 'freebl3.dll' failed
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  mozmake.EXE[4]: *** [freebl3.dll] Error 1
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  mozmake.EXE[4]: Leaving directory 'z:/task_1583182070/build/src/obj-firefox/security/nss/lib/freebl/freebl_freebl3'
[task 2020-03-02T21:45:00.110Z] 21:45:00     INFO -  Z:/task_1583182070/build/src/config/recurse.mk:74: recipe for target 'security/nss/lib/freebl/freebl_freebl3/target' failed
[task 2020-03-02T21:45:00.111Z] 21:45:00     INFO -  mozmake.EXE[3]: *** [security/nss/lib/freebl/freebl_freebl3/target] Error 2

Backout due to build failures in dependent bug 1617533: https://hg.mozilla.org/projects/nss/rev/4215a0b45a221bc4d0416eb458d3e2339711ef00

https://hg.mozilla.org/projects/nss/rev/7e09cdab32d0adac17ea3796c6837aba6fe5453f