Re-submit "Name function arguments in libc headers for Studio."

This reverts commit 9af9120091ceb96641d7c6c645fabad96db4bc0d (a revert
of 079bff4fa52b0c3c76057451cc9cdecf1827fce0), now the versioner bug is
fixed.

Bug: http://b/64613623 # header bug
Bug: http://b/64802958 # versioner bug
Change-Id: I1cb9d7832d4b3aecdc57a9285e2291443e59d02d
diff --git a/libc/include/sys/fsuid.h b/libc/include/sys/fsuid.h
index e4d9ebc..bb7a58d 100644
--- a/libc/include/sys/fsuid.h
+++ b/libc/include/sys/fsuid.h
@@ -34,9 +34,9 @@
 
 __BEGIN_DECLS
 
-int setfsuid(uid_t) __INTRODUCED_IN(21);
-int setfsgid(gid_t) __INTRODUCED_IN(21);
+int setfsuid(uid_t __uid) __INTRODUCED_IN(21);
+int setfsgid(gid_t __gid) __INTRODUCED_IN(21);
 
 __END_DECLS
 
-#endif /* _SYS_FSUID_H_ */
+#endif