ARC: Parse NOTE section in core dump files

New function elf32_arc_grok_parse to parse NOTE section in core dump files.
GDB requires this to work properly with core dumps.

GDB expects general purpose registers to be in section .reg. However Linux
kernel doesn't create this section and instead writes registers to NOTE
section. It is up to the binutils to create a pseudosection .reg from the
contents of NOTE. This patch adds this functionality to the ARC. Also BFD
will read from NOTE process id and signal number that caused failure. This
function relies on offsets inside elf_prstatus structure in Linux.

Signed-off-by: Anton Kolesov <akolesov@synopsys.com>