In gnulib, following many Unix systems, environ is declared in <unistd.h>.
There is no need to explicitly include <stdlib.h> in order to get it.
I'm applying this:
2008-12-16 Bruno Haible <br...@clisp.org>
* lib/unistd.in.h: Add comment.
* tests/test-environ.c: Don't include <stdlib.h>.
--- lib/unistd.in.h.orig 2008-12-17 01:51:46.000000000 +0100
+++ lib/unistd.in.h 2008-12-17 01:51:14.000000000 +0100
@@ -35,6 +35,7 @@
#endif
/* mingw fails to declare _exit in <unistd.h>. */
+/* mingw, BeOS, Haiku declare environ in <stdlib.h>, not in <unistd.h>. */
#include <stdlib.h>
#if @GNULIB_WRITE@ && @REPLACE_WRITE@ && @GNULIB_UNISTD_H_SIGPIPE@
--- tests/test-environ.c.orig 2008-12-17 01:51:46.000000000 +0100
+++ tests/test-environ.c 2008-12-17 00:08:11.000000000 +0100
@@ -20,7 +20,6 @@
#include <unistd.h>
-#include <stdlib.h>
#include <string.h>
int
