[exercises][ff-pm][cmake] Add labels for compilation

exercises/exercise-coupling-ff-pm/interface/CMakeLists.txt

 # executables for ex_interface_coupling_ff-pm
 dumux_add_test(NAME exercise_interface_coupling_ff-pm
-               SOURCES main.cc)
+               SOURCES main.cc
+               LABELS ffpm)
 
 # add a symlink for each input file
 add_input_file_links()

exercises/exercise-coupling-ff-pm/models/CMakeLists.txt

 # executables for ex_interface_coupling_ff-pm
 dumux_add_test(NAME exercise_models_coupling_ff-pm
-               SOURCES main.cc)
+               SOURCES main.cc
+               LABELS ffpm)
 
 # add a symlink for each input file
 add_input_file_links()

exercises/exercise-coupling-ff-pm/turbulence/CMakeLists.txt

 # executables for ex_interface_coupling_ff-pm
 dumux_add_test(NAME exercise_turbulence_coupling_ff-pm
-               SOURCES main.cc)
+               SOURCES main.cc
+               LABELS ffpm)
 
 # add a symlink for each input file
 add_input_file_links()

exercises/solution/exercise-coupling-ff-pm/interface/CMakeLists.txt

 dumux_add_test(NAME exercise_interface_coupling_ff-pm_original
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=0)
 
 dumux_add_test(NAME exercise_interface_coupling_ff-pm_a_solution
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=1)
 
 dumux_add_test(NAME exercise_interface_coupling_ff-pm_b_solution
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=2)
 
 dumux_add_test(NAME exercise_interface_coupling_ff-pm_c_solution
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=3)
 
 # add a symlink for each input file

exercises/solution/exercise-coupling-ff-pm/models/CMakeLists.txt

 dumux_add_test(NAME exercise_models_coupling_ff-pm_original
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=0
                COMMAND ${CMAKE_CURRENT_BINARY_DIR}/exercise_models_coupling_ff-pm_original
                CMD_ARGS -Problem.PlotStorage 0 -Problem.PlotFluxes 0)
 
 dumux_add_test(NAME exercise_models_coupling_ff-pm_a_solution
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=1
                COMMAND ${CMAKE_CURRENT_BINARY_DIR}/exercise_models_coupling_ff-pm_a_solution
                CMD_ARGS -Problem.PlotStorage 0 -Problem.PlotFluxes 0)
 
 dumux_add_test(NAME exercise_models_coupling_ff-pm_b_solution
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=2
                COMMAND ${CMAKE_CURRENT_BINARY_DIR}/exercise_models_coupling_ff-pm_b_solution
                CMD_ARGS -Problem.PlotStorage 0 -Problem.PlotFluxes 0)
 
 dumux_add_test(NAME exercise_models_coupling_ff-pm_c_solution
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=3
                COMMAND ${CMAKE_CURRENT_BINARY_DIR}/exercise_models_coupling_ff-pm_c_solution
                CMD_ARGS -Problem.PlotStorage 0 -Problem.PlotFluxes 0)

exercises/solution/exercise-coupling-ff-pm/turbulence/CMakeLists.txt

 dumux_add_test(NAME exercise_turbulence_coupling_ff-pm_original
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=0)
 
 dumux_add_test(NAME exercise_turbulence_coupling_ff-pm_a_solution
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=1)
 
 dumux_add_test(NAME exercise_turbulence_coupling_ff-pm_b_solution
                SOURCES main.cc
+               LABELS ffpm
                COMPILE_DEFINITIONS EXNUMBER=2)
 
 # add a symlink for each input file