[capturedb] don't fail on unparseable buck output

Summary:
Sometimes buck emits a timestamp, leading to a crash

> External Error: Failed to parse `buck targets --show-output ...` line of output:
> 2020-03-30 20:03:51

Reviewed By: dulmarod

Differential Revision: D20766438

fbshipit-source-id: 47cc00150

infer/src/integration/CaptureCompilationDatabase.ml

@@ -109,8 +109,9 @@ let get_compilation_database_files_buck db_deps ~prog ~args =
               | [_; filename] ->
                   `Raw filename :: compilation_database_files
               | _ ->
-                  L.(die ExternalError)
+                  L.internal_error
-                    "Failed to parse `buck targets --show-output ...` line of output:@\n%s" line
+                    "Failed to parse `buck targets --show-output ...` line of output:@\n%s" line ;
+                  compilation_database_files
             in
             List.fold ~f:scan_output ~init:[] lines
       in