Cast the fifth arg to mremap to void *

Summary:
Since the prototype of mremap is

```
void *mremap(void *old_address, size_t old_size, size_t new_size,
             int flags, ... /* void *new_address*/);
```
we need to cast new_address to void * when calling mremap.  Otherwise,
the wrong value will be passed to mremap on x32.

Patch by H.J Lu!

Reviewers: kcc, eugenis, samsonov

Subscribers: samsonov, llvm-commits

Differential Revision: http://reviews.llvm.org/D16805

llvm-svn: 259540