elf: Remove the property after reporting its removal

elf: Remove the property after reporting its removal

commit d2ef37ebd9f771d06edf1fdea37970f60b242b2d
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri Dec 7 08:30:30 2018 -0800

    elf: Report property change when merging properties

failed to remove the property after reporting it has been removed.  This
patch corrects it.

bfd/

	PR ld/24721
	* elf-properties.c (elf_merge_gnu_property_list): Remove the
	property after reporting property removal.

ld/

	PR ld/24721
	* testsuite/ld-x86-64/x86-64.exp: Run PR ld/24721 tests.
	* testsuite/ld-x86-64/pr24721-x32.d: New file.
	* testsuite/ld-x86-64/pr24721.d: Likewise.
	* testsuite/ld-x86-64/pr24721.map: Likewise.
	* testsuite/ld-x86-64/pr24721a.s: Likewise.
	* testsuite/ld-x86-64/pr24721b.s: Likewise.