suppress harmless error

su only exist in userdebug ROM, it is safe to mute it.
Bug: 196206162
Test: pass boot test

Change-Id: Ifacd5c51a2128306535f6de7bf38ec7e90325b12
diff --git a/vendor/google/dumpstate.te b/vendor/google/dumpstate.te
index 12a6a43..b3fc3dd 100644
--- a/vendor/google/dumpstate.te
+++ b/vendor/google/dumpstate.te
@@ -4,6 +4,7 @@
 userdebug_or_eng(`
   allow dumpstate debugfs_dma_buf:file r_file_perms;
   allow dumpstate media_rw_data_file:file append;
+  dontaudit dumpstate su:process sigkill;
 ')
 
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