tilegx: Check bfd_link_executable for TLS check

tilegx: Check bfd_link_executable for TLS check

Copied from x86, check bfd_link_executable, instead of bfd_link_pic,
for TLS transition check.  Not sure if it works correctly.  All usages
of bfd_link_pic should be audited.

	PR ld/22263
	* elfxx-tilegx.c (tilegx_elf_tls_transition): Replace
	bfd_link_pic with !bfd_link_executable, !bfd_link_pic with
	bfd_link_executable for TLS check.
	(tilegx_elf_check_relocs): Likewise.
	(allocate_dynrelocs): Likewise.
	(tilegx_elf_relocate_section): Likewise.