[AArch64] Use default_elf_asm_named_section instead of special cased hook

[AArch64] Use default_elf_asm_named_section instead of special cased hook

Hi,

The hook for TARGET_ASM_NAMED_SECTION was defined separately in
the backend around the time frame for GCC 4.7 under the assumption
that '@' would be used as a comment character in the binutils port.

This was indeed true in versions of the AArch64 port that never made it
into the FSF tree. However this practice was killed
before the binutils port made it upstream. Doing archaeology into
various revisions including the first commit of upstream binutils,
talking to Marcus about the history of this and actually testing the
first commit of binutils, I can confidently say that the upstream binutils
port never had any use of '@' as a comment character for AArch64
However we never got rid of the special cased handling in
GCC and the duplication of code in the AArch64 backend.

This was found when I was playing with Virtual Table verification
on ARM and AArch64 and discovered ICEs which were similar but manifested
in different places begging the obvious question.

Tested on aarch64-none-elf with no regressions.

Ok to apply ?

Ramana

2015-10-02  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>

	* config/aarch64/aarch64.c (aarch64_elf_asm_named_section): Delete.
	(TLS_SECTION_ASM_FLAG): Delete.

From-SVN: r228390