This performs *most* of the pcreectomy of b418e36f22.
It removes the tests and docs and all the large files, but it does
*not* touch any of the files except for making Find_Package
quiet (783a895b11) or remove the AUTHORS and similar files as
they are very small.
This seems much easier, cleaner, nicer and has 90% of the effect of
the old - the size now is 2.7MB instead of 2.1MB, down from 10MB.
Fixes#7599
