-#ifdef NOT_YET_IMPLEMENTED
-int mblen __P((const char *_s, size_t _n));
-size_t mbstowcs __P((wchar_t *_pwcs, const char *_s, size_t _n));
-int wctomb __P((char *_s, wchar_t _wchar));
-int mbtowc __P((wchar_t *_pwc, const char *_s, size_t _n));
-double strtod __P((const char *_nptr, char **_endptr));
-size_t wcstombs __P((char *_s, const wchar_t *_pwcs, size_t _n));
+#if !defined(_ANSI_SOURCE) && !defined(_POSIX_SOURCE)
+extern char *optarg; /* getopt(3) external variables */
+extern int opterr, optind, optopt;
+int getopt __P((int, char * const *, const char *));
+
+extern char *suboptarg; /* getsubopt(3) external variable */
+int getsubopt __P((char **, char * const *, char **));
+
+void *alloca __P((size_t)); /* built-in for gcc */
+int heapsort __P((void *, size_t, size_t,
+ int (*)(const void *, const void *)));
+char *initstate __P((unsigned, char *, int));
+int radixsort __P((const u_char **, int, const u_char *, u_int));
+long random __P((void));
+char *setstate __P((char *));
+void srandom __P((unsigned));
+void unsetenv __P((const char *));