We are reusing DEVICEATLAS_INC/DEVICEATLAS_LIB when the DeviceAtlas
library had been compiled and installed with cmake and make install targets.
Works fine except when ldconfig is unaware of the path, thus adding
cflags/ldflags into the mix.
Ideally, to be backported down to the lowest stable branch.
These were previously used for the "dadwsch" utility that's no longer
part of the addon, so we should not move the CFLAGS/LDFLAGS to the
global ones as this adds an undesired dependency on the libcurl and
libzip libs.
No backport is needed.
- Removing the legacy v2 support, which in turn suppress the need to set
a regex engine.
- Moving the options and addon into its distrinct build unit, cleaning up
the main one in the process.
- Adding a new option to disable the cache if desired or if
having a C++ toolchain is not a possibility.
