c-common.c, [...]: Fix comment typos.

	* c-common.c, cfgexpand.c, cgraphunit.c, defaults.h,
	et-forest.c, expr.c, gimplify.c, global.c, gthr-lynx.h,
	hard-reg-set.h, modulo-sched.c, optabs.c, postreload-gcse.c,
	tree-data-ref.c, tree-flow.h, tree-if-conv.c, tree-inline.c,
	tree-sra.c, tree-ssa-loop-im.c, tree-ssa-loop-ivopts.c,
	tree-ssa-loop-niter.c, tree-ssa-operands.c,
	tree-ssa-operands.h, tree-ssa-propagate.c,
	tree-ssa-propagate.h, tree-ssa-threadupdate.c, value-prof.c,
	vec.c, vec.h: Fix comment typos.  Follow spelling conventions.

From-SVN: r87104