message: Build with -fno-rtti.
  Per this guide to disabling exceptions in embedded C++:
  GPC: fno-rtti
diff: #
  Import("env")
  -# Threadsafe-statics ends up calling malloc. But we don't need them to be
  -# thread-safe because we don't have threads! This flag can't be in
  -# platformio.ini because gcc raises an error if it's provided to C code.
  -env.Append(CXXFLAGS=["-fno-threadsafe-statics"])
  +# Flags that can't be in platformio.ini because gcc raises an error if they're
  +# provided to C code.
  +env.Append(
  + CXXFLAGS=[
  + # Threadsafe-statics ends up calling malloc. But we don't need them to
  + # be thread-safe because we don't have threads!
  + "-fno-threadsafe-statics",
  + # Disable rtti per this guide to disabling exceptions in embedded C++:
  + # http://elegantinvention.com/blog/information/smaller-binary-size-with-c-on-baremetal-g/
  + "-fno-rtti",
  + ]
  +)
  # These link flags tell the linker that the processor we're using has
  # hardware floating point, so the software floating point libraries aren't
  