build hints

[mhaberler]

on a current raspbian this needs:

apt install libserial-dev libboost-all-dev

also, gps.cpp needs

#include <iostream>

or compilation fails with
$ g++ gps.cpp -o gps -lwiringPi -lserial -lm -std=c++11 gps.cpp: In function int main(): gps.cpp:42:2: error: cout was not declared in this scope cout.precision(10); ^

C++ version:

$ g++ --version

g++ (Raspbian 6.3.0-18+rpi1+deb9u1) 6.3.0 20170516