[RS6000] Remove TARGET_TLS_MARKERS and require binutils 2.20

[RS6000] Remove TARGET_TLS_MARKERS and require binutils 2.20

This patch removes !TARGET_TLS_MARKERS support.  -mtls-markers (and
-mno-tls-markers) disappear as valid options too, because I figure
they haven't been used too much except by people testing the
compiler.

	* config/rs6000/rs6000.opt (mtls-markers): Delete.
	* config/rs6000/rs6000.h (TARGET_TLS_MARKERS): Don't define.
	(IS_NOMARK_TLSGETADDR): Likewise.
	* config/rs6000/rs6000-protos.h (rs6000_output_tlsargs): Delete.
	* config/rs6000/rs6000.c (rs6000_output_tlsargs): Delete.
	(rs6000_legitimize_tls_address): Remove !TARGET_TLS_MARKERS code.
	(rs6000_call_template_1): Delete TARGET_TLS_MARKERS test and
	allow other UNSPECs besides UNSPEC_TLSGD and UNSPEC_TLSLD.
	(rs6000_indirect_call_template_1): Likewise.
	(rs6000_pltseq_template): Likewise.
	(rs6000_opt_vars): Remove "tls-markers" entry.
	* config/rs6000/rs6000.md (tls_gd<bits>): Replace TARGET_TLS_MARKERS
	with TARGET_ELF.
	(tls_gd_high<bits>, tls_gd_low<bits>): Likewise.
	(tls_ld<bits>, tls_ld_high<bits>, tls_ld_low<bits>): Likewise.
	(pltseq_plt_pcrel<mode>): Likewise.
	(call_value_local32): Remove IS_NOMARK_TLSGETADDR predicate test.
	(call_value_local64): Likewise.
	(call_value_indirect_nonlocal_sysv<mode>): Remove IS_NOMARK_TLSGETADDR
	output and length attribute sub-expression.
	(call_value_nonlocal_sysv<mode>),
	(call_value_nonlocal_sysv_secure<mode>),
	(call_value_local_aix<mode>, call_value_nonlocal_aix<mode>),
	(call_value_indirect_aix<mode>, call_value_indirect_elfv2<mode>),
	(call_value_indirect_pcrel<mode>): Likewise.
	* doc/install.texi (powerpc-*-*): Require binutils-2.20.
	* configure.ac (HAVE_AS_TLS_MARKERS): Delete test.
	* configure: Regenerate.
	* config.in: Regenerate.

From-SVN: r278075