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-arm64/syscalls/___mremap.S b/libc/arch-arm64/syscalls/___mremap.S
new file mode 100644
index 0000000..aeb93bc
--- /dev/null
+++ b/libc/arch-arm64/syscalls/___mremap.S
@@ -0,0 +1,15 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(___mremap)
+    mov     x8, __NR_mremap
+    svc     #0
+
+    cmn     x0, #(MAX_ERRNO + 1)
+    cneg    x0, x0, hi
+    b.hi    __set_errno_internal
+
+    ret
+END(___mremap)
+.hidden ___mremap