Revert "Name function arguments in libc headers for Studio."

This reverts commit 079bff4fa52b0c3c76057451cc9cdecf1827fce0.

Broke builds with SANITIZE_HOST=address with an asan failure in versioner.

Change-Id: I22b113fd5405589d1a25e5e137c450aaba1ade5f
diff --git a/libc/include/sys/signalfd.h b/libc/include/sys/signalfd.h
index 315622c..1e4d464 100644
--- a/libc/include/sys/signalfd.h
+++ b/libc/include/sys/signalfd.h
@@ -36,8 +36,8 @@
 
 __BEGIN_DECLS
 
-int signalfd(int __fd, const sigset_t* __mask, int __flags) __INTRODUCED_IN(18);
+int signalfd(int fd, const sigset_t* mask, int flags) __INTRODUCED_IN(18);
 
 __END_DECLS
 
-#endif
+#endif /* _SYS_SIGNALFD_H */