Reworked the UDev inclusion

* This fixes `SFML_DEPENDENCIES` missing the UDev library for static builds (issue SFML#728).

cmake/Modules/FindSFML.cmake

@@ -281,6 +281,7 @@ if(SFML_STATIC_LIBRARIES)
         if(FIND_SFML_OS_LINUX)
             find_sfml_dependency(X11_LIBRARY "X11" X11)
             find_sfml_dependency(XRANDR_LIBRARY "Xrandr" Xrandr)
+            find_sfml_dependency(UDEV_LIBRARY "UDev" udev)
         endif()
 
         # update the list
@@ -290,6 +291,8 @@ if(SFML_STATIC_LIBRARIES)
             set(SFML_WINDOW_DEPENDENCIES ${SFML_WINDOW_DEPENDENCIES} "GL" ${X11_LIBRARY} ${XRANDR_LIBRARY})
             if(FIND_SFML_OS_FREEBSD)
                 set(SFML_WINDOW_DEPENDENCIES ${SFML_WINDOW_DEPENDENCIES} "usbhid")
+            else()
+                set(SFML_WINDOW_DEPENDENCIES ${SFML_WINDOW_DEPENDENCIES} ${UDEV_LIBRARY})
             endif()
         elseif(FIND_SFML_OS_MACOSX)
             set(SFML_WINDOW_DEPENDENCIES ${SFML_WINDOW_DEPENDENCIES} "-framework OpenGL -framework Foundation -framework AppKit -framework IOKit -framework Carbon")

src/SFML/Window/CMakeLists.txt

@@ -199,25 +199,26 @@ if(NOT SFML_OPENGL_ES)
         endif()
         include_directories(${X11_INCLUDE_DIR})
     endif()
-    if(SFML_OS_LINUX)
-        find_package(UDev REQUIRED)
-        if(NOT UDEV_FOUND)
-            message(FATAL_ERROR "udev library not found")
-        endif()
-        include_directories(${UDEV_INCLUDE_DIR})
-    endif()
 endif()
 if(SFML_OPENGL_ES AND SFML_OS_LINUX)
     find_package(EGL REQUIRED)
     find_package(GLES REQUIRED)
     include_directories(${EGL_INCLUDE_DIR} ${GLES_INCLUDE_DIR})
 endif()
+if(SFML_OS_LINUX)
+    find_package(UDev REQUIRED)
+    if(NOT UDEV_FOUND)
+        message(FATAL_ERROR "udev library not found")
+    endif()
+    include_directories(${UDEV_INCLUDE_DIR})
+endif()
+
 
 # build the list of external libraries to link
 if(SFML_OS_WINDOWS)
     list(APPEND WINDOW_EXT_LIBS winmm gdi32)
 elseif(SFML_OS_LINUX)
-    list(APPEND WINDOW_EXT_LIBS ${X11_X11_LIB} ${X11_Xrandr_LIB} ${UDEV_LIBRARIES})
+    list(APPEND WINDOW_EXT_LIBS ${X11_X11_LIB} ${X11_Xrandr_LIB} ${UDEV_LIBRARY})
 elseif(SFML_OS_FREEBSD)
     list(APPEND WINDOW_EXT_LIBS ${X11_X11_LIB} ${X11_Xrandr_LIB} usbhid)
 elseif(SFML_OS_MACOSX)