`-Wvla` compiler warnings

[zfields]

~/.arduino15/packages/arduino/hardware/mbed_opta/4.1.5/libraries/SocketWrapper/src/MbedUdp.cpp: In member function 'virtual int arduino::MbedUDP::endPacket()':
~/.arduino15/packages/arduino/hardware/mbed_opta/4.1.5/libraries/SocketWrapper/src/MbedUdp.cpp:76:22: warning: variable length array 'buffer' is used [-Wvla]
   uint8_t buffer[size];
                      ^

[zfields]

arduino-cli compile --verbose --warnings=all --build-property "build.extra_flags=-Wno-implicit-fallthrough -Wno-psabi -Wno-deprecated-copy -Wno-missing-field-initializers -Wno-delete-non-virtual-dtor -Wno-sign-compare -Og -g" --fqbn arduino:mbed_opta:opta <dev_folder>