[sched-deps] Generalise usage of macro fusion to work on any two insns.

[sched-deps] Generalise usage of macro fusion to work on any two insns.

	* sched-deps.c (try_group_insn): Generalise macro fusion hook usage
	to any two insns.  Update comment.  Rename to sched_macro_fuse_insns.
	(sched_analyze_insn): Update use of try_group_insn to
	sched_macro_fuse_insns.
	* config/i386/i386.c (ix86_macro_fusion_pair_p): Reject 2nd
	arguments that are not conditional jumps.

Co-Authored-By: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
From-SVN: r213551