Hide accidentally-exposed __clock_nanosleep.

Bug: http://b/21858067
Change-Id: Iaa83a5e17cfff796aed4f641d0d14427614d9399
diff --git a/libc/arch-arm/syscalls/___clock_nanosleep.S b/libc/arch-arm/syscalls/___clock_nanosleep.S
new file mode 100644
index 0000000..31420bb
--- /dev/null
+++ b/libc/arch-arm/syscalls/___clock_nanosleep.S
@@ -0,0 +1,15 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(___clock_nanosleep)
+    mov     ip, r7
+    ldr     r7, =__NR_clock_nanosleep
+    swi     #0
+    mov     r7, ip
+    cmn     r0, #(MAX_ERRNO + 1)
+    bxls    lr
+    neg     r0, r0
+    b       __set_errno_internal
+END(___clock_nanosleep)
+.hidden ___clock_nanosleep