Looking at this page https://cryptopp.com/wiki/CMake#Using_the_library_in_other_projects
it seems to me there should be or there is going to be a system-wide
official FindCryptoPP module. Those changes should match the case convention
from that page... somewhat. I'm not going to do the cryptopp-shared thing.
So *if* that official module will ever become available on mainstream distros,
and *if* they start using proper names, this file should just be deleted
and everything should keep on working just fine.
Allows to pass -march=native to dindxer projects and to libpqtypes.
CMake min version raised to 3.3 since externalproject_add didn't
support generator expressions prior to that version.
