Fix build by avoiding the _C_LABEL macro.

Change-Id: Ide367c2b65071388bd95fbc81a4ed6ae94aec4e4
diff --git a/libc/arch-x86_64/syscalls/mmap.S b/libc/arch-x86_64/syscalls/mmap.S
index d6f9687..9c3fc0f 100644
--- a/libc/arch-x86_64/syscalls/mmap.S
+++ b/libc/arch-x86_64/syscalls/mmap.S
@@ -16,5 +16,5 @@
     ret
 END(mmap)
 
-    .globl _C_LABEL(mmap64)
-    .equ _C_LABEL(mmap64), _C_LABEL(mmap)
+    .globl mmap64
+    .equ mmap64, mmap