[llvm-readelf] Fix core note descriptions

Summary:
Core files have different descriptions for note values. llvm-readelf currently prints the generic note type, which is wrong when using it to read a core file.

To verify the constants/strings, see:
Values: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=include/elf/common.h;h=75c4fb7e9d7c0f780d635ac305f579546b7b071b;hb=HEAD#l571
Strings: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=binutils/readelf.c;h=c31a5c1266b7bb62a485895b01b49e1f832ade35;hb=HEAD#l16881

Note: this does not handle printing the note data for NT_FILE, it just fixes the descriptions.

Reviewers: MaskRay

Reviewed By: MaskRay

Subscribers: labath, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65608

llvm-svn: 367878