x86: Add GNU_PROPERTY_X86_UINT32_VALID

x86: Add GNU_PROPERTY_X86_UINT32_VALID

The older linker treats .note.gnu.property section as a generic note
and just concatenates all .note.gnu.property sections from the input
to the output.  On CET-enabled OS, the output of the older linker is
marked as CET enabled, but in fact, it is not CET enabled and it crashes
on CET-enabled machines.

This patch defines GNU_PROPERTY_X86_UINT32_VALID.  Linker is updated to
set the GNU_PROPERTY_X86_UINT32_VALID bit in GNU property note for
non-relocatable output to differentiate outputs from the older linker.

bfd/

	* elfxx-x86.c (_bfd_x86_elf_parse_gnu_properties): Mask out the
	GNU_PROPERTY_X86_UINT32_VALID bit.
	(_bfd_x86_elf_link_fixup_gnu_properties): Set the
	GNU_PROPERTY_X86_UINT32_VALID bit for non-relocatable output.

binutils/

	* readelf.c (print_gnu_property_note): Check the
	GNU_PROPERTY_X86_UINT32_VALID bit for invalid GNU property note.

include/

	* elf/common.h (GNU_PROPERTY_X86_UINT32_VALID): New.