Add splice, tee, and vmsplice.

Change-Id: I5f43380b88d776a8bb607b47dbbc5db5a2fe6163

libc/arch-x86_64/syscalls/vmsplice.S

@@ -0,0 +1,16 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(vmsplice)
+    movq    %rcx, %r10
+    movl    $__NR_vmsplice, %eax
+    syscall
+    cmpq    $-MAX_ERRNO, %rax
+    jb      1f
+    negl    %eax
+    movl    %eax, %edi
+    call    __set_errno
+1:
+    ret
+END(vmsplice)