DRY: Reduce duplication in platform Makefiles

Move builds for non-avr target (simulator) into a $(BUILD_FLAVOR)
build subdir (build/sim) to isolate it more completely and
cleanly from the AVR builds.  This allows AVR and SIM to use common
build rules again.

Move newly bits out of Makefile-{SIM,AVR} and into Makefile-common.

Makefile-AVR

@@ -127,6 +127,7 @@ CFLAGS += -Os
 CFLAGS += -ffunction-sections
 CFLAGS += -finline-functions-called-once
 CFLAGS += -mcall-prologues
+CFLAGS += -Wa,-adhlns=$(@:.o=.al)
 
 LDFLAGS  = -Wl,--as-needed
 
@@ -141,8 +142,6 @@ endif
 
 LIBS  = -lm
 
-OBJ = $(patsubst %.c,$(BUILDDIR)/%.o,$(SOURCES))
-
 -include Makefile-common
 
 # Architecture specific targets

Makefile-SIM

@@ -35,6 +35,7 @@
 TARGET = sim
 
 SIM_PATH = simulator
+BUILD_FLAVOR = $(TARGET)
 
 # Arduino IDE takes the "compile everything available"-approach, so we have
 # to keep this working and can take a shortcut:
@@ -43,7 +44,6 @@ SOURCES = $(wildcard *.c)
 SIM_SOURCES = $(subst $(SIM_PATH)/,,$(wildcard $(SIM_PATH)/*.c))
 SOURCES := $(filter-out $(subst _sim.c,.c,$(SIM_SOURCES)),$(SOURCES)) $(SIM_SOURCES)
 
-OBJ = $(patsubst %.c,$(BUILDDIR)/%.sim.o,$(SOURCES))
 CFLAGS += -g -Wall -Wstrict-prototypes -Wno-format -Os $(DEFS) -std=gnu99
 CFLAGS += -funsigned-char -funsigned-bitfields -fshort-enums -I.. -I.
 CFLAGS += -DSIMULATOR
@@ -55,13 +55,7 @@ CFLAGS += -D__AVR_ATmega1280__
 
 include Makefile-common
 
-$(BUILDDIR)/%.sim.o: %.c | $(BUILDDIR)
-	@echo "  CC        $@"
-	@cc -c $(CFLAGS) -MMD -o $@ $<
-	@$(call CCPOST)
-
-$(TARGET): $(OBJ)
-	@echo "  LINK      $@"
-	@cc $(CFLAGS) -o $@ $^
+$(TARGET): $(BUILDDIR)/$(TARGET).elf
+	cp $< $@
 
 vpath %.c $(SIM_PATH)

Makefile-common

@@ -34,6 +34,10 @@
 BUILDDIR = build
 USER_CONFIG ?= config.h
 
+ifdef BUILD_FLAVOR
+BUILDDIR := $(BUILDDIR)/$(BUILD_FLAVOR)
+endif
+
 ifneq ($(USER_CONFIG),config.h)
 BUILDDIR := $(BUILDDIR)/$(USER_CONFIG:.h=)
 endif
@@ -45,6 +49,8 @@ OBJDUMP = $(TOOLCHAIN)objdump
 OBJCOPY = $(TOOLCHAIN)objcopy
 
 
+OBJ = $(patsubst %.c,$(BUILDDIR)/%.o,$(SOURCES))
+
 .PHONY: all clean doc functionsbysize
 .PRECIOUS: %.o %.elf
 
@@ -79,7 +85,7 @@ endef
 
 $(BUILDDIR)/%.o: %.c | $(BUILDDIR)
 	@echo "  CC        $@"
-	@$(CC) -c $(CFLAGS) -MMD -Wa,-adhlns=$(@:.o=.al) -o $@ $<
+	@$(CC) -c $(CFLAGS) -MMD -o $@ $<
 	@$(call CCPOST)
 
 $(BUILDDIR)/%.elf: $(OBJ)