fix initgroups (uninitialized count passed to getgrouplist)

src/linux/initgroups.c

@@ -9,7 +9,7 @@ int setgroups(size_t, const gid_t *);
 int initgroups(const char *user, gid_t gid)
 {
 	gid_t groups[NGROUPS_MAX];
-	int count;
+	int count = NGROUPS_MAX;
 	if (getgrouplist(user, gid, groups, &count) < 0) return -1;
 	return setgroups(count, groups);
 }