xfail more cases of complaints about relocs in read-only sections

	* testsuite/ld-elf/comm-data5.d: xfail targets that complain
	about dynamic relocations in read-only sections.
	* testsuite/ld-elf/ehdr_start-shared.d: Likewise.
	* testsuite/ld-elf/ehdr_start.d: Likewise.
	* testsuite/ld-scripts/pr22267.d: Likewise.
	* testsuite/ld-elf/shared.exp: Likewise for DT_TEXTREL tests and
	pr20995 text.
	* testsuite/ld-elf/sec64k.exp: Don't run 64ksec on lm32-linux.