Added check for HAVE_SYSERRLIST to get rid of redefinition warning when using autoconf.

cmd/xfe/mozilla.h

@@ -40,8 +40,10 @@ extern int putenv (const char *);
 
 #if defined(LINUX) && defined(__GLIBC__) && (__GLIBC__ >= 2)
 #define LINUX_GLIBC_2
+#ifndef HAVE_SYSERRLIST
 #define HAVE_SYSERRLIST
 #endif
+#endif
 
 #endif /* __xfe_mozilla_h_ */