Introduce generic variant targets

Change Makefiles to allow multiple binary targets specified by VARIANT
environment variabel. For specified variants a matching main-<VARIANT>.c
source file must be present.

Makefile

@@ -1,12 +1,10 @@
 #CONFIGURE BUILD SYSTEM
+TARGET	   = MDBench-$(TAG)
 BUILD_DIR  = ./$(TAG)
-SRC_DIR    = ./src/core
+SRC_DIR    = ./src
 MAKE_DIR   = ./
 Q         ?= @
 
-TARGET_MDBENCH	   = MDBench-$(TAG)
-TARGET_STUB        = stub
-
 #DO NOT EDIT BELOW
 include $(MAKE_DIR)/config.mk
 include $(MAKE_DIR)/include_$(TAG).mk
@@ -23,31 +21,23 @@ endif
 
 VPATH     = $(SRC_DIR)
 ASM       = $(patsubst $(SRC_DIR)/%.c, $(BUILD_DIR)/%.s,$(wildcard $(SRC_DIR)/*.c))
-OBJ       = $(patsubst $(SRC_DIR)/%.c, $(BUILD_DIR)/%.o,$(wildcard $(SRC_DIR)/*.c))
+OBJ       = $(filter-out $(BUILD_DIR)/main%,$(patsubst $(SRC_DIR)/%.c, $(BUILD_DIR)/%.o,$(wildcard $(SRC_DIR)/*.c)))
 CPPFLAGS := $(CPPFLAGS) $(DEFINES) $(OPTIONS) $(INCLUDES)
 
-all: ${TARGET_MDBENCH} ${TARGET_STUB}
+ifneq ($(VARIANT),)
+	.DEFAULT_GOAL := ${TARGET}-$(VARIANT)
+endif
 
-${TARGET_MDBENCH}: $(BUILD_DIR) $(OBJ) $(BUILD_DIR)/main.o
-	@echo "===>  LINKING  $(TARGET_MDBENCH)"
-	$(Q)${LINKER} ${LFLAGS} -o $(TARGET_MDBENCH) $(OBJ) $(BUILD_DIR)/main.o $(LIBS)
+${TARGET}: $(BUILD_DIR) $(OBJ) $(SRC_DIR)/main.c
+	@echo "===>  LINKING  $(TARGET)"
+	$(Q)${LINKER} $(CPPFLAGS) ${LFLAGS} -o $(TARGET) $(SRC_DIR)/main.c $(OBJ) $(LIBS)
 
-${TARGET_STUB}: $(BUILD_DIR) $(OBJ) $(BUILD_DIR)/stub.o
-	@echo "===>  LINKING  $(TARGET_STUB)"
-	$(Q)${LINKER} ${LFLAGS} -o $(TARGET_STUB) $(OBJ) $(BUILD_DIR)/stub.o $(LIBS)
+${TARGET}-%: $(BUILD_DIR) $(OBJ) $(SRC_DIR)/main-%.c
+	@echo "===>  LINKING  $(TARGET)-$* "
+	$(Q)${LINKER} $(CPPFLAGS) ${LFLAGS} -o $(TARGET)-$* $(SRC_DIR)/main-$*.c $(OBJ) $(LIBS)
 
 asm:  $(BUILD_DIR) $(ASM)
 
-$(BUILD_DIR)/main.o: ./src/main.c
-	@echo "===>  COMPILE  $@"
-	$(Q)$(CC) -c $(CPPFLAGS) $(CFLAGS) $< -o $@
-	$(Q)$(CC) $(CPPFLAGS) -MT $(@:.d=.o) -MM  $< > $(BUILD_DIR)/main.d
-
-$(BUILD_DIR)/stub.o: ./src/stub.c
-	@echo "===>  COMPILE  $@"
-	$(Q)$(CC) -c $(CPPFLAGS) $(CFLAGS) $< -o $@
-	$(Q)$(CC) $(CPPFLAGS) -MT $(@:.d=.o) -MM  $< > $(BUILD_DIR)/stub.d
-
 $(BUILD_DIR)/%.o:  %.c
 	@echo "===>  COMPILE  $@"
 	$(Q)$(CC) -c $(CPPFLAGS) $(CFLAGS) $< -o $@

src/main-stub.c

@@ -39,9 +39,9 @@ void init(Parameter *param) {
 }
 
 // Show debug messages
-//#define DEBUG  printf
+//#define DEBUG(msg)  printf(msg)
 // Do not show debug messages
-#define DEBUG
+#define DEBUG(msg)
 
 #define ADD_ATOM(x, y, z, vx, vy, vz)   atom_x(atom->Nlocal) = base_x + x * NEIGH_DISTANCE; \
                                         atom_y(atom->Nlocal) = base_y + y * NEIGH_DISTANCE; \