cmake: Include avif INTERFACE_INCLUDE_DIRECTORIES first

Fixes #233

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3a71322..bf67ae2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -326,6 +326,7 @@
     target_link_libraries(avifenc avif ${AVIF_PLATFORM_LIBRARIES} ${ZLIB_LIBRARY} ${PNG_LIBRARY} ${JPEG_LIBRARY})
     target_include_directories(avifenc
                                PRIVATE
+                                   $<TARGET_PROPERTY:avif,INTERFACE_INCLUDE_DIRECTORIES>
                                    ${CMAKE_CURRENT_SOURCE_DIR}/apps/shared
                                    ${ZLIB_INCLUDE_DIR}
                                    ${PNG_PNG_INCLUDE_DIR}
@@ -345,6 +346,7 @@
     target_link_libraries(avifdec avif ${AVIF_PLATFORM_LIBRARIES} ${ZLIB_LIBRARY} ${PNG_LIBRARY} ${JPEG_LIBRARY})
     target_include_directories(avifdec
                                PRIVATE
+                                   $<TARGET_PROPERTY:avif,INTERFACE_INCLUDE_DIRECTORIES>
                                    ${CMAKE_CURRENT_SOURCE_DIR}/apps/shared
                                    ${ZLIB_INCLUDE_DIR}
                                    ${PNG_PNG_INCLUDE_DIR}