fix #143 by setting LIB_INSTALL_DIR CMake var

Author: schmittlauch

CMakeLists.txt

@@ -225,6 +225,10 @@ set(include_install_dir "include")
 
 set(generated_dir "${CMAKE_CURRENT_BINARY_DIR}/generated")
 
+if (NOT LIB_INSTALL_DIR)
+	set (LIB_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/lib")
+endif (NOT LIB_INSTALL_DIR)
+
 # Configuration
 set(version_config "${generated_dir}/${PROJECT_NAME}ConfigVersion.cmake")
 set(project_config "${generated_dir}/${PROJECT_NAME}Config.cmake")