alias.c, [...]: Fix comment typos.

	* alias.c, crtstuff.c, dbxout.c, domwalk.c, domwalk.h, gcc.c,
	gcse.c, global.c, lambda-code.c, loop.c, mips-tdump.c,
	optabs.h, predict.c, reg-stack.c, regclass.c, sched-rgn.c,
	tree-optimize.c, tree-ssa-dom.c, tree-ssa-forwprop.c,
	tree-ssa-operands.c, tree-ssa-phiopt.c,
	tree-ssa-threadupdate.c: Fix comment typos.

From-SVN: r87707