[llvm-readobj] - Teach llvm-readobj to dump .note.gnu.property sections.

NT_GNU_PROPERTY_TYPE_0 is a recently added type of .note.gnu.property
section specified in Linux Extensions to gABI.
(https://github.com/hjl-tools/linux-abi/wiki/Linux-Extensions-to-gABI)

Patch teach tool to print such notes properly.

Differential revision: https://reviews.llvm.org/D44469

llvm-svn: 328078