Linux: Add an evdev based controller backend, to replace SDL.

CMakeTests/FindLibudev.cmake

@@ -0,0 +1,28 @@
+# - Try to find LIBUDEV
+# Once done this will define
+#  LIBUDEV_FOUND - System has LIBUDEV
+#  LIBUDEV_INCLUDE_DIRS - The LIBUDEV include directories
+#  LIBUDEV_LIBRARIES - The libraries needed to use LIBUDEV
+
+FIND_PATH(
+    LIBUDEV_INCLUDE_DIR libudev.h
+    /usr/include
+    /usr/local/include
+    ${LIBUDEV_PATH_INCLUDES}
+)
+
+FIND_LIBRARY(
+    LIBUDEV_LIBRARY
+    NAMES udev libudev
+    PATHS ${ADDITIONAL_LIBRARY_PATHS}
+        ${LIBUDEV_PATH_LIB}
+)
+
+set(LIBUDEV_LIBRARIES ${LIBUDEV_LIBRARY} )
+set(LIBUDEV_INCLUDE_DIRS ${LIBUDEV_INCLUDE_DIR} )
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(LIBUDEV  DEFAULT_MSG
+                                  LIBUDEV_LIBRARY LIBUDEV_INCLUDE_DIR)
+
+mark_as_advanced(LIBUDEV_INCLUDE_DIR LIBUDEV_LIBRARY )