auto merge of #15404 : vhbit/rust/ios-ptr-fixes, r=pcwalton

Author: bors

src/libstd/rt/backtrace.rs

@@ -261,7 +261,7 @@ mod imp {
         use slice::{MutableVector};
 
         extern {
-            fn backtrace(buf: *mut *const libc::c_void,
+            fn backtrace(buf: *mut *mut libc::c_void,
                          sz: libc::c_int) -> libc::c_int;
         }
 
@@ -274,7 +274,7 @@ mod imp {
         try!(writeln!(w, "stack backtrace:"));
         // 100 lines should be enough
         static SIZE: libc::c_int = 100;
-        let mut buf: [*const libc::c_void, ..SIZE] = unsafe {mem::zeroed()};
+        let mut buf: [*mut libc::c_void, ..SIZE] = unsafe {mem::zeroed()};
         let cnt = unsafe { backtrace(buf.as_mut_ptr(), SIZE) as uint};
 
         // skipping the first one as it is write itself