Description of problem:

    tests: fix bug-1319374.c compile warnings.

    I was looking at a downstream failure of bug-1319374-THIS-crash.t when I
    saw the compiler was throwing a warning while running the test:

    tests/bugs/gfapi/bug-1319374.c:17:61: warning: implicit declaration of function ‘strerror’; did you mean ‘perror’? [-Wimplicit-function-declaration]
             fprintf(stderr, "\nglfs_new: returned NULL (%s)\n", strerror(errno));
                                                                 ^~~~~~~~
                                                                 perror

    So I compiled the .c with -Wall and saw a lot many more warnings, all
    due of a missing header.