Help with making a port C11 compliant

[Walter Schwarzenfeld]

Now the test with gcc47 is finish,it does not work with poudriere. But 
gcc48 and gcc5.
The

/CXXFLAGS+= -D_GLIBCXX_USE_C99 flag is used in two dozens of ports (if 
you look in the portstree) for same or similiar reasons, I think it will 
be ok./