FreeRTOS_Plus_TCP_Echo_Posix depends on Libslirp library to emulate network interface.
Make sure libslirp and glib (libslirp dependency) are installed before building the demo:
1. Run sudo apt-get install -y git build-essential libglib2.0-dev libslirp-dev in Ubuntu OS
2. Run brew install libslirp in MacOS
