UDP packets are always received as OOB data. Without checking for
new OOB data with a call to "_process_oob" then recv_udp never blocks.
If a UDP packet is not available then NSAPI_ERROR_WOULD_BLOCK is
returned. This causes mbed-os's DNS handling to always fail when
flow control is enabled.
This patch fixes recv_udp by always calling "_process_oob" regardless
of if flow control is enabled. This ensures that recv_udp follows the
timeout parameter and waits for new data to arrive.
mbed.h has 'using namespace mbed;', hence some of the files skip
adding required namespace to the code, it is always good to specify the
namespace around the elements in header and `using namespace` in
specific CPP files, instead of all
Compile [ 1.3%]: ESP8266Interface.cpp
[Error] ESP8266Interface.cpp@582,33: cannot declare static function inside another function
[Error] ESP8266Interface.cpp@583,13: cannot convert 'ESP8266Interface (*)()' to 'WiFiInterface*' in return
Failed to build library
Russ Butler
Veijo Pesonen
Cruz Monrreal
deepikabhavnani
paul-szczepanek-arm
Juha Ylinen
Seppo Takalo