build(meson): fix CMake Config file include dir

I previously set the path to ${CMAKE_CURRENT_LIST_FILE}/include,
that was wrong and ended up pointing to a nonexistent directory.
diff --git a/cmake/meson-config.cmake.in b/cmake/meson-config.cmake.in
index 9aeef78..3fdb3e7 100644
--- a/cmake/meson-config.cmake.in
+++ b/cmake/meson-config.cmake.in
@@ -3,6 +3,6 @@
 if(NOT TARGET @TARGET_NAME@)
 	add_library(@TARGET_NAME@ INTERFACE IMPORTED)
 	set_target_properties(@TARGET_NAME@ PROPERTIES
-		INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_CURRENT_LIST_FILE}/include"
+		INTERFACE_INCLUDE_DIRECTORIES "@ABSOLUTE_INCLUDE_DIR@"
 	)
 endif()
diff --git a/meson.build b/meson.build
index 59d0051..1634fd0 100644
--- a/meson.build
+++ b/meson.build
@@ -35,6 +35,7 @@
 	
 	cmake_conf = configuration_data()
 	cmake_conf.set('TARGET_NAME', meson.project_name() + '::' + meson.project_name())
+	cmake_conf.set('ABSOLUTE_INCLUDE_DIR', get_option('prefix')/get_option('includedir'))
 	
 	cmake.configure_package_config_file(
 		name: meson.project_name(),