Work around porting bugs reported by Dieter in <http://lists.gnu.org/archive/html/bug-bison/2006-01/msg00049.html>. * lib/getopt.c (_NOPROTO): Remove; no longer needed. Include <stdlib.h> and <unistd.h> in all environments; it's safe now. Include "getopt.h" first, to check interface. (getenv): Declare only if defined HAVE_DECL_GETENV && !HAVE_DECL_GETENV. * lib/strndup.c [!_LIBC]: Include "strndup.h" to get prototype. (__strndup): Revert to K&R-style function dfns, the glibc style. * lib/strnlen.c: Don't claim it's taken from glibc; it's not. (strnlen, __strnlen): Remove #defines and #undefs; not needed. Include strnlen.h first, to get prototype properly. (strnlen): Renamed from __strnlen. Remove weak alias. * m4/getopt.m4 (gl_PREREQ_GETOPT): Check for getenv decl.