Add -fno-exceptions to default build config

* C++ exceptions are expensive and are not used in our code
* We need to disable exception to achieve desired behavior for
  std::stoi, which we don't want it to crash when failing to parse an
  incoming integer

Test: make, net_test_osi
Change-Id: Idc363ff1f25f085c75df3c473ee4d2a210af3b17