cppdiropts.texi: Merge documentation of -I, -iquote, -isystem, and -idirafter.

cppdiropts.texi: Merge documentation of -I, -iquote, -isystem, and -idirafter.

2017-01-07  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* doc/cppdiropts.texi: Merge documentation of -I, -iquote,
	-isystem, and -idirafter.  Copy-edit.
	* doc/cppopts.texi: Copy-edit.  Remove contradiction about
	default for -ftrack-macro-expansion.  Delete obsolete and
	badly-formatted implementation details about -fdebug-cpp output.
	* doc/cppwarnopts.texi: Copy-edit.

From-SVN: r244200