Removes the -DBUILD_COMPONENTS option; on by default now.

Quick follow up for #3570:
there is no reason not to build the `osrm-components` tool by defualt.

Backwards compatible. Users still specifying the option will see:

> Manually-specified variables were not used by the project:
>   BUILD_COMPONENTS

CMakeLists.txt

@@ -17,7 +17,6 @@ endif()
 option(ENABLE_MASON "Use mason for dependencies" OFF)
 option(ENABLE_CCACHE "Speed up incremental rebuilds via ccache" ON)
 option(BUILD_TOOLS "Build OSRM tools" OFF)
-option(BUILD_COMPONENTS "Build osrm-components" OFF)
 option(BUILD_PACKAGE "Build OSRM package" OFF)
 option(ENABLE_ASSERTIONS "Use assertions in release mode" OFF)
 option(ENABLE_COVERAGE "Build with coverage instrumentalisation" OFF)
@@ -613,11 +612,10 @@ target_link_libraries(osrm_contract ${CONTRACTOR_LIBRARIES})
 target_link_libraries(osrm_extract ${EXTRACTOR_LIBRARIES})
 target_link_libraries(osrm_store ${STORAGE_LIBRARIES})
 
-if(BUILD_COMPONENTS)
-  add_executable(osrm-components src/tools/components.cpp $<TARGET_OBJECTS:UTIL>)
-  target_link_libraries(osrm-components ${TBB_LIBRARIES} ${BOOST_BASE_LIBRARIES})
-  install(TARGETS osrm-components DESTINATION bin)
-endif()
+# BUILD_COMPONENTS
+add_executable(osrm-components src/tools/components.cpp $<TARGET_OBJECTS:UTIL>)
+target_link_libraries(osrm-components ${TBB_LIBRARIES} ${BOOST_BASE_LIBRARIES})
+install(TARGETS osrm-components DESTINATION bin)
 
 if(BUILD_TOOLS)
   message(STATUS "Activating OSRM internal tools")