[RS6000] No inline PLT for V4 bss-plt, implement -mno-pltseq

[RS6000] No inline PLT for V4 bss-plt, implement -mno-pltseq

Inline PLT calls need PLT to be an array of addresses.  PowerPC 32-bit
bss-plt works differently, so this patch disables inline PLT calls
when -mbss-plt.  The patch also adds support for a new -mno-pltseq
option, which may be required when linking with -mbss-plt code.

	* doc/invoke.texi (man page RS/6000 and PowerPC Options): Mention
	-mlongcall and -mpltseq.
	(RS/6000 and PowerPC Options <-mlongcall>): Mention inline PLT calls.
	(RS/6000 and PowerPC Options <-mpltseq>): Document.
	* config/rs6000/rs6000.h (TARGET_PLTSEQ): Define.
	* config/rs6000/sysv4.opt (mpltseq): New option.
	* config/rs6000/sysv4.h (TARGET_PLTSEQ): Redefine.
	(SUBTARGET_OVERRIDE_OPTIONS): Error if given -mpltseq when assembler
	support is lacking.  Don't allow -mpltseq with -mbss-plt.
	* config/rs6000/linux64.h (SUBSUBTARGET_OVERRIDE_OPTIONS): Warn if
	-mpltseq given for ELFv1.
	* config/rs6000/rs6000.c (rs6000_call_aix): Comment on UNSPEC_PLTSEQ.
	Only use UNSPEC_PLTSEQ for inline PLT calls.
	(rs6000_call_sysv, rs6000_sibcall_sysv): Expand comments.  Only
	use UNSPEC_PLTSEQ for inline PLT calls.
	(rs6000_indirect_call_template_1, rs6000_longcall_ref),
	(rs6000_call_aix, rs6000_call_sysv, rs6000_sibcall_sysv): Replace
	uses of HAVE_AS_PLTSEQ with TARGET_PLTSEQ, simplifying.
	* config/rs6000/rs6000.md (pltseq_tocsave_<mode>),
	(pltseq_plt16_ha_<mode>, pltseq_plt16_lo_<mode>),
	(pltseq_mtctr_<mode>): Likewise.

From-SVN: r268770