maint: Remove redundant 'environ' declarations.

* src/rexecd.c: Remove 'extern char **environ' and instead rely on the
gnulib declaration in unistd.h.
* src/rshd.c: Likewise.
* src/uucpd.c: Likewise.
* telnet/commands.c: Likewise.
* telnetd/pty.c: Likewise.
* tests/addrpeek.c: Likewise.

src/rexecd.c

@@ -216,7 +216,6 @@ char *envinit[] = { homedir, shell, path, username,
   logname, remotehost, NULL
 };
 #endif
-extern char **environ;
 
 char *getstr (const char *);
 

src/rshd.c

@@ -417,7 +417,6 @@ char rhost[128 + sizeof ("RHOST=")] = "RHOST=";
 #ifndef WITH_PAM
 char *envinit[] = { homedir, shell, path, logname, username, rhost, NULL };
 #endif
-extern char **environ;
 
 void
 doit (int sockfd, struct sockaddr *fromp, socklen_t fromlen)

src/uucpd.c

@@ -103,8 +103,6 @@ char *nenv[] = {
   NULL,
 };
 
-extern char **environ;
-
 static struct argp_option argp_options[] = {
 #define GRP 10
   {"uucico", 'u', "LOCATION", 0,

telnet/commands.c

@@ -58,6 +58,7 @@
 #include <netinet/in.h>
 
 #include <fcntl.h>
+#include <unistd.h>
 
 #include <signal.h>
 #include <netdb.h>
@@ -1886,7 +1887,6 @@ env_find (const char *var)
 void
 env_init (void)
 {
-  extern char **environ;
   register char **epp, *cp;
   register struct env_lst *ep;
 #ifndef strchr

telnetd/pty.c

@@ -83,7 +83,6 @@ startslave (char *host, int autologin, char *autoname)
   return master;
 }
 
-extern char **environ;
 /*
  * scrub_env()
  *

tests/addrpeek.c

@@ -56,13 +56,6 @@
 # define SEPARATOR "\n"
 #endif
 
-/* TODO Develop some reliable test for the existence of ENVIRON.
- * It is detectable using HAVE_DECL_ENVIRON for GNU/Linux and
- * GNU/kFreeBSD. It is present, but not detectable for OpenBSD
- * and FreeBSD.
- */
-extern char **environ;
-
 static void
 write_address (int fd)
 {