Fix build by avoiding the _C_LABEL macro.

Change-Id: Ide367c2b65071388bd95fbc81a4ed6ae94aec4e4
diff --git a/libc/arch-arm64/syscalls/ftruncate.S b/libc/arch-arm64/syscalls/ftruncate.S
index 7ed80b9..c8f5b6b 100644
--- a/libc/arch-arm64/syscalls/ftruncate.S
+++ b/libc/arch-arm64/syscalls/ftruncate.S
@@ -20,5 +20,5 @@
     ret
 END(ftruncate)
 
-    .globl _C_LABEL(ftruncate64)
-    .equ _C_LABEL(ftruncate64), _C_LABEL(ftruncate)
+    .globl ftruncate64
+    .equ ftruncate64, ftruncate