[BZ #18572] arm: Disable lazy initialization of tlsdesc entries

[BZ #18572] arm: Disable lazy initialization of tlsdesc entries

Follow up to
https://sourceware.org/ml/libc-alpha/2015-11/msg00272.html

Always do tls descriptor initialization at load time during relocation
processing (as if DF_BIND_NOW were set for the binary) to avoid barriers
at every tls access.  This patch mimics bind-now semantics in the lazy
relocation code of the arm target (elf_machine_lazy_rel).

Ideally the static linker should be updated too to not emit tlsdesc
relocs in DT_REL*, so elf_machine_lazy_rel is not called on them at all.

	[BZ #18572]
	* sysdeps/arm/dl-machine.h (elf_machine_lazy_rel): Do symbol binding
	non-lazily for R_ARM_TLS_DESC.