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
similarity index 84%
rename from libc/arch-x86_64/syscalls/mremap.S
rename to libc/arch-x86_64/syscalls/___mremap.S
index a6042cb..cc6dee9 100644
--- a/libc/arch-x86_64/syscalls/mremap.S
+++ b/libc/arch-x86_64/syscalls/___mremap.S
@@ -2,7 +2,7 @@
 
 #include <private/bionic_asm.h>
 
-ENTRY(mremap)
+ENTRY(___mremap)
     movq    %rcx, %r10
     movl    $__NR_mremap, %eax
     syscall
@@ -13,4 +13,5 @@
     call    __set_errno_internal
 1:
     ret
-END(mremap)
+END(___mremap)
+.hidden ___mremap