basic/glob-util: add closedir wrapper to silence gcc

basic/glob-util: add closedir wrapper to silence gcc

../src/test/test-glob-util.c: In function 'test_glob_no_dot':
../src/test/test-glob-util.c:61:32: warning: cast between incompatible function types from 'int (*)(DIR *)' {aka 'int (*)(struct __dirstream *)'} to 'void (*)(void *)' [-Wcast-function-type]
                 .gl_closedir = (void (*)(void *)) closedir,
                                ^