Do no crash if a requested resource is not available [

(cherry picked from commit 95ee482)

third_party/bazel/src/main/protobuf/failure_details.proto

@@ -746,6 +746,7 @@ message LocalExecution {
   enum Code {
     LOCAL_EXECUTION_UNKNOWN = 0 [(metadata) = { exit_code: 37 }];
     LOCKFREE_OUTPUT_PREREQ_UNMET = 1 [(metadata) = { exit_code: 2 }];
+    UNTRACKED_RESOURCE = 2 [(metadata) = { exit_code: 1 }];
   }
 
   Code code = 1;