fix the mremap signature

The mremap definition was incorrect (unsigned long instead of int) and
it was missing the optional new_address parameter.

Change-Id: Ib9d0675aaa098c21617cedc9b2b8cf267be3aec4
diff --git a/libc/arch-x86_64/syscalls/___mremap.S b/libc/arch-x86_64/syscalls/___mremap.S
new file mode 100644
index 0000000..cc6dee9
--- /dev/null
+++ b/libc/arch-x86_64/syscalls/___mremap.S
@@ -0,0 +1,17 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(___mremap)
+    movq    %rcx, %r10
+    movl    $__NR_mremap, %eax
+    syscall
+    cmpq    $-MAX_ERRNO, %rax
+    jb      1f
+    negl    %eax
+    movl    %eax, %edi
+    call    __set_errno_internal
+1:
+    ret
+END(___mremap)
+.hidden ___mremap