Name function arguments in libc headers for Studio.

Second batch of headers...

Bug: http://b/64613623
Test: builds
Change-Id: I8eef043dbf32afee8ff814e9d005f46aee8fa21f
diff --git a/libc/include/sys/eventfd.h b/libc/include/sys/eventfd.h
index 6b9749a..3cfb5e7 100644
--- a/libc/include/sys/eventfd.h
+++ b/libc/include/sys/eventfd.h
@@ -37,14 +37,13 @@
 #define EFD_CLOEXEC O_CLOEXEC
 #define EFD_NONBLOCK O_NONBLOCK
 
-/* type of event counter */
 typedef uint64_t eventfd_t;
 
-int eventfd(unsigned int initial_value, int flags);
+int eventfd(unsigned int __initial_value, int __flags);
 
-int eventfd_read(int fd, eventfd_t* value);
-int eventfd_write(int fd, eventfd_t value);
+int eventfd_read(int __fd, eventfd_t* __value);
+int eventfd_write(int __fd, eventfd_t __value);
 
 __END_DECLS
 
-#endif /* _SYS_EVENTFD_H */
+#endif