3.6.1 nominations for libc++abi

[Eric Fiselier]

Hi Tom,
CC Marshall

I nominate the following patches to be included in 3.6.1.

These two commits clean up undefined behavior in readEncodedPointer.

- r231839: Fix PR21580 - Undefined behavior in readEncodedPointer()
  https://llvm.org/bugs/show_bug.cgi?id=21580
  https://github.com/llvm-mirror/libcxxabi/commit/89ea9ad0b0a48a9b9fccf6de81bdca1861960855

- r231852: Remove unneeded const_cast in readPointerHelper. Pointed
out by jroelofs
  https://github.com/llvm-mirror/libcxxabi/commit/fdd39fd838828bba84c4f7ad620207ae0d734ad5


These commits how libc++abi matches exception types to catch blocks.
In particular it makes libc++abi properly check for multilevel pointer
conversions as well as void* conversions.


- r233984: Fix multi-level pointer conversions and pointer to member
conversion detection.
  https://github.com/llvm-mirror/libcxxabi/commit/0cb62d1b51f3d9ab65e0ba7b6541dda0663fe50d

- r234254: Disallow Base to Derived conversions for catching pointers
to members.
  https://github.com/llvm-mirror/libcxxabi/commit/554d59ab0b989830273c9183f7bdfd12108cad7a

- r236299: Disallow conversions from function pointers to void*.
  https://github.com/llvm-mirror/libcxxabi/commit/b979db159a515fe12b54f793690618313e017259

/Eric