* auto-inc-dec.c, c-incpath.c, config/c4x/libgcc.S,
	config/sh/divcost-analysis, dbgcnt.def, df-core.c,
	df-problems.c, df-scan.c, df.h, dominance.c, dse.c, regstat.c,
	tree-data-ref.c, tree-ssa-loop-im.c, tree-ssa-loop-prefetch.c,
	tree-vect-transform.c: Fix comment typos.  Follow spelling
	conventions.

From-SVN: r125666