* c-incpath.c (add_sysroot_to_chain): New.
	(merge_include_chains): Add sysroot argument.  Call
	add_sysroot_to_chain if sysrooted.
	(register_include_chains): Update call to merge_include_chains.
	* doc/cppopts.texi: Document use of '=' in include directory
	arguments.

From-SVN: r123134