* c-typeck.c, cfgexpand.c, ddg.c, ddg.h, df.c, fold-const.c,
	gcov.c, gimplify.c, modulo-sched.c, passes.c, tree-cfg.c,
	tree-mudflap.c, tree-nrv.c, tree-outof-ssa.c, tree-ssa-dom.c,
	tree-ssa-dse.c, tree-ssa-operands.c, tree-ssa-pre.c,
	tree-tailcall.c: Fix comment typos.  Follow spelling
	conventions.

From-SVN: r83703