Add files in third_party/fiat for Chromium to pick up.

Chromium's licenses.py is a little finicky.

Change-Id: I015a3565eb8f3cfecb357d142facc796a9c80888
Reviewed-on: https://boringssl-review.googlesource.com/24784
Reviewed-by: Adam Langley <agl@google.com>

third_party/fiat/BUILD.gn

@@ -0,0 +1,4 @@
+# This is an dummy target so Chromium's tools/licenses.py script picks up the
+# extra README.chromium file. The script expects README.chromium files to be
+# associated with GN targets.
+source_set("fiat_license") { }

third_party/fiat/README.chromium

@@ -0,0 +1,10 @@
+Name: Fiat-Crypto: Synthesizing Correct-by-Construction Code for Cryptographic Primitives
+Short Name: fiat-crypto
+URL: https://github.com/mit-plv/fiat-crypto
+Version: git (see METADATA)
+License: MIT
+License File: LICENSE
+Security Critical: yes
+
+Description:
+See README.md and METADATA.