Do not install CMakeLists.txt in loader/register

By including the installation of a whole directory in the source code
for loader/register, the buildsystem is installing the CMakeLists.txt
files that are included in these directories. Exclude them from the
final installation by using the EXCLUDE clause in CMake.

Signed-off-by: Jose Luis Rivero <jrivero@osrfoundation.org>

register/CMakeLists.txt

@@ -3,4 +3,5 @@ ign_add_component(register INTERFACE)
 
 install(
   DIRECTORY include/
-  DESTINATION ${IGN_INCLUDE_INSTALL_DIR_FULL})
+  DESTINATION ${IGN_INCLUDE_INSTALL_DIR_FULL}
+  PATTERN "CMakeLists.txt" EXCLUDE)