* cfglayout.c, cgraphunit.c, config/avr/avr.c, fold-const.c,
	haifa-sched.c, optabs.h, tree-affine.c, tree-data-ref.c,
	tree-predcom.c, tree-ssa-alias-warnings.c,
	tree-ssa-forwprop.c, tree-vect-analyze.c, tree-vrp.c: Fix
	comment typos.  Follow spelling conventions.
	* doc/cpp.texi, doc/invoke.texi: Fix typos.

From-SVN: r125080