Use VDSO for clock_gettime(2) and gettimeofday(2).

Bug: 15387103

(cherry picked from commit 625993dfbb085a3cde7492eda8ec1cdc1ee39a78)

Change-Id: I0e156d7049ba1495902259071a96936592e74025
diff --git a/libc/arch-x86_64/syscalls/__clock_gettime.S b/libc/arch-x86_64/syscalls/__clock_gettime.S
new file mode 100644
index 0000000..7e553b8
--- /dev/null
+++ b/libc/arch-x86_64/syscalls/__clock_gettime.S
@@ -0,0 +1,16 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(__clock_gettime)
+    movl    $__NR_clock_gettime, %eax
+    syscall
+    cmpq    $-MAX_ERRNO, %rax
+    jb      1f
+    negl    %eax
+    movl    %eax, %edi
+    call    __set_errno
+1:
+    ret
+END(__clock_gettime)
+.hidden __clock_gettime