We don't use getgrouplist() at the moment so there's no need to

provide a compat version.

include/missing.h

@@ -78,8 +78,5 @@ int unsetenv(const char *);
 #ifndef HAVE_STRSIGNAL
 char *strsignal(int);
 #endif
-#ifndef HAVE_GETGROUPLIST
-int getgrouplist(const char *name, gid_t basegid, gid_t *groups, int *ngroups);
-#endif
 
 #endif /* _SUDO_MISSING_H */