Add support for the utimensat(2) syscall to bionic.

The kernel has supported this syscall for quite some time now,
but bionic did not.  Now that there is a need for it, let's
add it to bionic.

Change-Id: Ifcef3e46f1438d79435b600c4e6063857ab16903
diff --git a/libc/arch-arm/syscalls.mk b/libc/arch-arm/syscalls.mk
index 5210d6c..e6c84f6 100644
--- a/libc/arch-arm/syscalls.mk
+++ b/libc/arch-arm/syscalls.mk
@@ -124,6 +124,7 @@
 syscall_src += arch-arm/syscalls/__timer_getoverrun.S
 syscall_src += arch-arm/syscalls/__timer_delete.S
 syscall_src += arch-arm/syscalls/utimes.S
+syscall_src += arch-arm/syscalls/utimensat.S
 syscall_src += arch-arm/syscalls/sigaction.S
 syscall_src += arch-arm/syscalls/sigprocmask.S
 syscall_src += arch-arm/syscalls/__sigsuspend.S