Rename snow2mdl source code files with .F90 extension.

Ref ufs-community#973.

sorc/emcsfc_snow2mdl.fd/makefile

@@ -21,18 +21,18 @@ LIBS= $(G2_LIBd) $(IP_LIBd) $(SP_LIBd) $(LANDSFCUTIL_LIBd) $(BACIO_LIB4) \
 $(CMD):	$(OBJS)
 	$(FCOMP) $(FFLAGS) -o $(CMD) $(OBJS) $(LIBS)
 
-driver.o: snowdat.o model_grid.o snow2mdl.o program_setup.o driver.f
-	$(FCOMP) $(FFLAGS) -c driver.f
-program_setup.o: program_setup.f
-	$(FCOMP) $(FFLAGS) -c program_setup.f
-snowdat.o: program_setup.o model_grid.o snowdat.f
-	$(FCOMP) $(FFLAGS) -I$(G2_INCd) -c snowdat.f
-model_grid.o: program_setup.o model_grid.f
-	$(FCOMP) $(FFLAGS) -I$(G2_INCd) -c model_grid.f
-snow2mdl.o: snowdat.o program_setup.o model_grid.o snow2mdl.f
-	$(FCOMP) $(FFLAGS) -I$(LANDSFCUTIL_INCd) -I$(G2_INCd) -c snow2mdl.f
-grib_utils.o: grib_utils.f
-	$(FCOMP) $(FFLAGS) -I$(G2_INCd) -c grib_utils.f
+driver.o: snowdat.o model_grid.o snow2mdl.o program_setup.o driver.F90
+	$(FCOMP) $(FFLAGS) -c driver.F90
+program_setup.o: program_setup.F90
+	$(FCOMP) $(FFLAGS) -c program_setup.F90
+snowdat.o: program_setup.o model_grid.o snowdat.F90
+	$(FCOMP) $(FFLAGS) -I$(G2_INCd) -c snowdat.F90
+model_grid.o: program_setup.o model_grid.F90
+	$(FCOMP) $(FFLAGS) -I$(G2_INCd) -c model_grid.F90
+snow2mdl.o: snowdat.o program_setup.o model_grid.o snow2mdl.F90
+	$(FCOMP) $(FFLAGS) -I$(LANDSFCUTIL_INCd) -I$(G2_INCd) -c snow2mdl.F90
+grib_utils.o: grib_utils.F90
+	$(FCOMP) $(FFLAGS) -I$(G2_INCd) -c grib_utils.F90
 all: check_prereqs $(CMD)
 clean:
 	rm -f *.o *.mod $(CMD) ../../exec/$(CMD)