Remove the useless _C_LABEL from generated system calls.

Change-Id: Id1d2fd39972652831ea825f6f9cf940b08f42b5c
diff --git a/libc/arch-arm64/syscalls/__sched_getaffinity.S b/libc/arch-arm64/syscalls/__sched_getaffinity.S
index 9b785ad..58715d0 100644
--- a/libc/arch-arm64/syscalls/__sched_getaffinity.S
+++ b/libc/arch-arm64/syscalls/__sched_getaffinity.S
@@ -19,4 +19,4 @@
 
     ret
 END(__sched_getaffinity)
-.hidden _C_LABEL(__sched_getaffinity)
+.hidden __sched_getaffinity