Name function arguments in libc headers for Studio.

First batch of headers...

Bug: http://b/64613623
Test: builds
Change-Id: I6bc3ad79daa635456b61d03b1f43f06c433ec596
diff --git a/libc/include/android/legacy_signal_inlines.h b/libc/include/android/legacy_signal_inlines.h
index 09db2a6..4d474b0 100644
--- a/libc/include/android/legacy_signal_inlines.h
+++ b/libc/include/android/legacy_signal_inlines.h
@@ -39,7 +39,7 @@
 
 #if __ANDROID_API__ < __ANDROID_API_L__
 
-sighandler_t bsd_signal(int signum, sighandler_t handler) __REMOVED_IN(21);
+sighandler_t bsd_signal(int __signal, sighandler_t __handler) __REMOVED_IN(21);
 
 /* These weren't introduced until L. */
 int __libc_current_sigrtmax() __attribute__((__weak__)) __VERSIONER_NO_GUARD;