[WINDOWSNT]: Don't declare getenv.

nt/config.nt

@@ -378,6 +378,7 @@ Boston, MA 02111-1307, USA.  */
 #endif
 #endif
 
+#ifndef WINDOWSNT
 /* Some of the files of Emacs which are intended for use with other
    programs assume that if you have a config.h file, you must declare
    the type of getenv.
@@ -387,6 +388,7 @@ Boston, MA 02111-1307, USA.  */
 #ifndef NOT_C_CODE
 extern char *getenv ();
 #endif
+#endif
 
 #endif /* EMACS_CONFIG_H */