Add vs2019 to vs_toolchain.py.

VS2015 has finally dropped off our support window. As part of dropping
it from the bots, I'm thinking of using the current vs2017 builders to
test vs2019. In preparation for that, add a vs2019 hash to
vs_toolchain.py.

Change-Id: I4c3dde2825f57c39a8da0e155e96d08550d39893
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/52005
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
diff --git a/util/bot/vs_toolchain.py b/util/bot/vs_toolchain.py
index 051d78b..2c2ca03 100644
--- a/util/bot/vs_toolchain.py
+++ b/util/bot/vs_toolchain.py
@@ -70,6 +70,10 @@
     # Debuggers, and 10.0.17134 version of d3dcompiler_47.dll, with ARM64
     # libraries.
     return ['418b3076791776573a815eb298c8aa590307af63']
+  if version == '2019':
+    # VS 2019 16.61 with 10.0.19041 SDK, and 10.0.20348 version of
+    # d3dcompiler_47.dll, with ARM64 libraries and UWP support.
+    return ['3bda71a11e']
   raise Exception('Unsupported VS version %s' % version)