Remove the useless _C_LABEL from generated system calls.

Change-Id: Id1d2fd39972652831ea825f6f9cf940b08f42b5c
diff --git a/libc/arch-arm64/syscalls/__syslog.S b/libc/arch-arm64/syscalls/__syslog.S
index 625a7eb..2e1fb1d 100644
--- a/libc/arch-arm64/syscalls/__syslog.S
+++ b/libc/arch-arm64/syscalls/__syslog.S
@@ -19,4 +19,4 @@
 
     ret
 END(__syslog)
-.hidden _C_LABEL(__syslog)
+.hidden __syslog