This updates the include path used when this project is used/consumed
via find_package(). The include paths no longer need to be prefixed
with 'QtZeroConf', and so now they can be included the same regardless
of whether this project is being used via FetchContent or find_package
Signed-off-by: Marc Reilly <marc@cpdesign.com.au>
Unfortunately, there is no FindAvahi.cmake file available. Instead use
find_library and find_path to find the libavahi-client.so and
avahi-client/client.h files. This improves logging if the files are not found
and allows to use CMAKE_FIND_ROOT_PATH to alter the search paths for
crossplatform builds.
* Add `project`
* Remove hardcoded values for controlling the library type (i.e. shared
or static) in favour of using `BUILD_SHARED_LIBS` and letting CMake
manage the rest
* Fix linker error (at least on Windows w/ MinGW) that
'legacy_stdio_definitions.lib' couldn't be found
