Pack Utf8Proc stuff

Make the package required when USE_UTF8PROC IS ON.
Use target_compile_definitions(), target_include_directories() and
target_link_libraries().

CMakeLists.txt

@@ -53,12 +53,7 @@ include(qtermwidget5_use)
 option(USE_UTF8PROC "Use libutf8proc for better Unicode support. Default OFF" OFF)
 
 if(USE_UTF8PROC)
-    find_package(Utf8Proc)
-endif()
-
-if (UTF8PROC_FOUND)
-    add_definitions(-DHAVE_UTF8PROC)
-    include_directories("${UTF8PROC_INCLUDE_DIRS}")
+    find_package(Utf8Proc REQUIRED)
 endif()
 
 # main library
@@ -148,8 +143,19 @@ set_target_properties( ${QTERMWIDGET_LIBRARY_NAME} PROPERTIES
                        VERSION ${QTERMWIDGET_VERSION}
                      )
 if (UTF8PROC_FOUND)
-    target_link_libraries(${QTERMWIDGET_LIBRARY_NAME} ${UTF8PROC_LIBRARIES})
+    target_compile_definitions(${QTERMWIDGET_LIBRARY_NAME}
+        PRIVATE
+            "HAVE_UTF8PROC"
+    )
+    target_include_directories(${QTERMWIDGET_LIBRARY_NAME}
+        INTERFACE
+            ${UTF8PROC_INCLUDE_DIRS}
+    )
+    target_link_libraries(${QTERMWIDGET_LIBRARY_NAME}
+        ${UTF8PROC_LIBRARIES}
+    )
 endif()
+
 if(APPLE)
     set (CMAKE_SKIP_RPATH 1)
     # this is a must to load the lib correctly