Add initial HRSS support.

This change includes support for a variant of [HRSS], a post-quantum KEM
based on NTRU. It includes changes suggested in [SXY]. This is not yet
ready for any deployment: some breaking changes, like removing the
confirmation hash, are still planned.

(CLA for HRSS's assembly code noted in b/119426559.)

[HRSS] https://eprint.iacr.org/2017/667.pdf
[SXY] https://eprint.iacr.org/2017/1005.pdf

Change-Id: I85d813733b066d5c578484bdd248de3f764194db
Reviewed-on: https://boringssl-review.googlesource.com/c/33105
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/util/generate_build_files.py b/util/generate_build_files.py
index 9c635dc..44db7f5 100644
--- a/util/generate_build_files.py
+++ b/util/generate_build_files.py
@@ -43,6 +43,10 @@
     ('linux', 'arm'): [
         'src/crypto/curve25519/asm/x25519-asm-arm.S',
         'src/crypto/poly1305/poly1305_arm_asm.S',
+        'src/crypto/hrss/asm/poly_mul_vec_armv7_neon.S',
+    ],
+    ('linux', 'x86_64'): [
+        'src/crypto/hrss/asm/poly_rq_mul.S',
     ],
 }