PR22263 ld test

PR22263 ld test

A number of targets that I test regularly fail the "Build pr22263-1"
test for various reasons.

arm-linux-gnueabi: "undefined reference to `__aeabi_read_tp'"
ia64-linux-gnu: "Explicit stops are ignored in auto mode"
m68k-linux-gnu: "undefined reference to `__m68k_read_tp'"
microblaze-linux-gnu: "undefined reference to `__tls_get_addr'"
nios2-linux-gnu, s390-linux-gnu and sh4-linux-gnu have a tprel reloc in .got
riscv64-linux-gnu has a dynamic relocation in text

So only riscv really fails the pr.  The rest fail due to test issues
or lack of a linker optimisation.  Lack of an optimisation isn't
really a fail, but it's worth keeping the test to ensure those
optimisations don't regress.  The xfail targets may not be an
exhaustive list.  This just tidies test results for those for which I
have cross compilers installed.

	PR 22263
	* testsuite/ld-elf/tls.exp: Split pr22263 test into two parts,
	one to check for -z text errors, the other to check tprel
	linker optimisation.  Supply needed symbols and assembler flags.
	xfail the linker optimisation on targets known to fail.