Fix build by avoiding the _C_LABEL macro.

Change-Id: Ide367c2b65071388bd95fbc81a4ed6ae94aec4e4
diff --git a/libc/arch-x86_64/syscalls/pwrite64.S b/libc/arch-x86_64/syscalls/pwrite64.S
index 96215ce..1ada9d9 100644
--- a/libc/arch-x86_64/syscalls/pwrite64.S
+++ b/libc/arch-x86_64/syscalls/pwrite64.S
@@ -16,5 +16,5 @@
     ret
 END(pwrite64)
 
-    .globl _C_LABEL(pwrite)
-    .equ _C_LABEL(pwrite), _C_LABEL(pwrite64)
+    .globl pwrite
+    .equ pwrite, pwrite64