With libstdc++ in libc, __futex_wait and __futex_wake can be hidden.

This patch is conservative and just touches LP64. (But not because we
know of anyone using this in LP32.)

Bug: 13367666
Change-Id: Id45652debc4534584479b16b501401f6f23acea9
diff --git a/libc/arch-arm64/bionic/futex_arm64.S b/libc/arch-arm64/bionic/futex_arm64.S
index d452771..5a47826 100644
--- a/libc/arch-arm64/bionic/futex_arm64.S
+++ b/libc/arch-arm64/bionic/futex_arm64.S
@@ -51,7 +51,7 @@
 END(__futex_syscall3)
 
 // int __futex_wait(volatile void* ftx, int val, const struct timespec* timeout)
-ENTRY(__futex_wait)
+ENTRY_PRIVATE(__futex_wait)
   stp x29, x30, [sp, #-16]!
   mov x29, sp
 
@@ -69,7 +69,7 @@
 END(__futex_wait)
 
 // int __futex_wake(volatile void* ftx, int count)
-ENTRY(__futex_wake)
+ENTRY_PRIVATE(__futex_wake)
   stp x29, x30, [sp, #-16]!
   mov x29, sp