Align struct passwd definition with other variations of libc

Add pg_gecos ("real name") field to struct passwd.

Bug: 14679430
Bug: 12875898
Change-Id: I833ec2c46f6a6259b7232a8e3f7942968ef0b50d
diff --git a/tests/stubs_test.cpp b/tests/stubs_test.cpp
index 7d70aa6..9b0c231 100644
--- a/tests/stubs_test.cpp
+++ b/tests/stubs_test.cpp
@@ -41,6 +41,10 @@
   EXPECT_STREQ(username, pwd->pw_name);
   EXPECT_EQ(uid, pwd->pw_uid);
   EXPECT_EQ(uid, pwd->pw_gid);
+  ASSERT_EQ(NULL, pwd->pw_passwd);
+#ifdef __LP64__
+  ASSERT_EQ(NULL, pwd->pw_gecos);
+#endif
 
   if (uid_type == TYPE_SYSTEM) {
     EXPECT_STREQ("/", pwd->pw_dir);