libfileis(3): finish removal

include/libfileis.h

@@ -1,14 +0,0 @@
-int fileis_block  (char *fn);
-int fileis_char   (char *fn);
-int fileis_dir    (char *fn);
-/*  fileis_exec   (char *fn); */
-int fileis_exists (char *fn);
-int fileis_fifo   (char *fn);
-int fileis_setgid (char *fn);
-int fileis_link   (char *fn);
-/*  fileis_read   (char *fn); */
-int fileis_regular(char *fn);
-int fileis_socket (char *fn);
-int fileis_setuid (char *fn);
-int fileis_vtx    (char *fn);
-/*  fileis_write  (char *fn); */