x86-64: Remove sframe relocs against discarded sections

x86-64: Remove sframe relocs against discarded sections

Since unlike eh_frame editing code, sframe editing code keeps
R_X86_64_NONE reloc as is, its r_offset is wrong, we must not
generate R_X86_64_NONE reloc in sframe section against discarded
sections for "ld -r".

bfd/

	PR ld/33156
	* elf64-x86-64.c (elf_x86_64_relocate_section): Also remove
	sframe relocations against discarded sections for "ld -r".

ld/

	PR ld/33156
	* testsuite/ld-elf/eh-group.exp (as_gsframe): New.
	Assemble eh-group.o with $as_gsframe.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>