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/swap.h b/libc/include/sys/swap.h
index e79af97..8a30cce 100644
--- a/libc/include/sys/swap.h
+++ b/libc/include/sys/swap.h
@@ -38,9 +38,9 @@
 #define SWAP_FLAG_PRIO_MASK 0x7fff
 #define SWAP_FLAG_PRIO_SHIFT 0
 
-int swapon(const char*, int) __INTRODUCED_IN(19);
-int swapoff(const char*) __INTRODUCED_IN(19);
+int swapon(const char* __path,  int __flags) __INTRODUCED_IN(19);
+int swapoff(const char* __path) __INTRODUCED_IN(19);
 
 __END_DECLS
 
-#endif /* _SYS_SWAP_H_ */
+#endif