toolchain: create artifact of clang crash diagnoses

Automatically identify clang crashes and create an artifact with source
code and run scripts that reproduce the issues for further diagnosis.

BUG=chromium:1056904
TEST=Standalone test.

Cq-Depend: chromium:2243612, chromium:2251038
Change-Id: I1ff0367fb1a29040ec32063e9df4dd6dd4306956
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2243766
Commit-Queue: Jian Cai <jiancai@google.com>
Tested-by: Jian Cai <jiancai@google.com>
Reviewed-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
diff --git a/api/controller/toolchain.py b/api/controller/toolchain.py
index 6191462..cc80ec8 100644
--- a/api/controller/toolchain.py
+++ b/api/controller/toolchain.py
@@ -77,6 +77,9 @@
         _Handlers('ChromeAFDOProfileForAndroidLinux',
                   toolchain_util.PrepareForBuild,
                   toolchain_util.BundleArtifacts),
+    BuilderConfig.Artifacts.CLANG_CRASH_DIAGNOSES:
+        _Handlers('ClangCrashDiagnoses', toolchain_util.PrepareForBuild,
+                  toolchain_util.BundleArtifacts),
 }