message: test: Document why no symbol names can be used for suppressions
diff: # -fsanitize=undefined suppressions
  # =================================
  -signed-integer-overflow:CTxMemPool::PrioritiseTransaction
  +# This would be `signed-integer-overflow:CTxMemPool::PrioritiseTransaction`,
  +# however due to a bug in clang the symbolizer is disabled and thus no symbol
  +# names can be used.
  +# See https://github.com/google/sanitizers/issues/1364
  +signed-integer-overflow:txmempool.cpp
  # -fsanitize=integer suppressions
  # ===============================
  