Add preadv/pwritev.

Bug: http://b/12612572
Change-Id: I38ff2684d69bd0fe3f21b1d371b88fa60d5421cb
diff --git a/libc/arch-mips64/syscalls/preadv.S b/libc/arch-mips64/syscalls/preadv.S
new file mode 100644
index 0000000..df43a8d
--- /dev/null
+++ b/libc/arch-mips64/syscalls/preadv.S
@@ -0,0 +1,27 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(preadv)
+    .set push
+    .set noreorder
+    li v0, __NR_preadv
+    syscall
+    bnez a3, 1f
+    move a0, v0
+    j ra
+    nop
+1:
+    move t0, ra
+    bal     2f
+    nop
+2:
+    .cpsetup ra, t1, 2b
+    LA t9,__set_errno_internal
+    .cpreturn
+    j t9
+    move ra, t0
+    .set pop
+END(preadv)
+
+ALIAS_SYMBOL(preadv64, preadv)