#Description:

The package `extra/sdl2_ttf` is configured incorrectly, which causes problems when working with CMake:
```
find_package(SDL2_ttf REQUIRED)
...
target_link_libraries(Test SDL2_ttf::SDL2_ttf)
```
We get an error. Due to misconfigured `${prefix}` or `${includedir}` in `sdl2_ttf-config.cmake`:
```
CMake Error in CMakeLists.txt:
Imported target "SDL2_ttf::SDL2_ttf" includes non-existent path

"//include/SDL2"

in its INTERFACE_INCLUDE_DIRECTORIES. Possible reasons include:

* The path was deleted, renamed, or moved to another location.

* An install or uninstall procedure did not complete successfully.

* The installation package was faulty and references files it does not
provide.
```

#Additional info:
- Version: sdl2_ttf 2.20.2-1
- Arch: x86_64

#Steps to reproduce:
- Download and unpack the attached producer.
- Execute `cmake .` in producer folder.

#Note
There is a possibility that `sdl2_image` and `sdl2_mixer` are subject to the same error, since the cmake support code is similar.