sites.

do_cmd_ignorePlatformAnnotation(),
do_cmd_platform(),
do_cmd_platformof():  New functions to support platform dependency
		      information.

process_all_platformofs():  New function to post-process \platformof macros
	using information collected during the initial pass.

process_python_state():  New function. Call all post-processing functions
	defined in this file to avoid having to have too much knowledge of
	the internals for this stuff in l2hinit.perl.