ld: aarch64: fix TLS relaxation where TCB_SIZE is used

ld: aarch64: fix TLS relaxation where TCB_SIZE is used

TCB_SIZE is 2*sizeof(void *), which is 0x10 for lp64, and 0x8 for
ilp32. During relaxation, ld goes to do a replace:
bl   __tls_get_addr => add R0, R0, TCB_SIZE

But actual implementation is:
bfd_putl32 (0x91004000, contents + rel->r_offset + 4);

Which is equivalent of add x0, x0, 0x10. This is wrong for ilp32.

The possible fix for it is:
bfd_putl32 (0x91000000 | (TCB_SIZE<<10), contents + rel->r_offset + 4);

But ilp32 also needs w-registers, so it's simpler to put proper
instruction in #if/#else condition.

THere are 2 such relaxations in elfNN_aarch64_tls_relax(), and so 2 new
tests added for ilp32 mode to test it.

Yury