Move build intermediate files into a subdir

The root dir was getting hairy, so this moves build files
into the build directory.  This also reduces the chance of
build errors with any other projects sharing the lufa library.

Signed-off-by: Vernon Mauery <vernon@mauery.com>

Author: vmauery

.gitignore

@@ -1,3 +1,4 @@
+build/
 tmp/
 doc/
 lufa

Makefile

@@ -91,7 +91,7 @@ BUILD_TYPE = debug
 # Object files directory
 #     To put object files in current directory, use a dot (.), do NOT make
 #     this an empty or blank macro!
-OBJDIR = .
+OBJDIR = build
 
 
 # Path to the LUFA library
@@ -114,6 +114,7 @@ SRC = $(TARGET).c                                              \
    ringbuffer.c                                                \
    sprintf.c                                                   \
    descriptors.c                                               \
+   settings.sig.h                                              \
    settings.c                                                  \
    $(LUFA_PATH)/LUFA/Drivers/USB/LowLevel/Device.c             \
    $(LUFA_PATH)/LUFA/Drivers/USB/LowLevel/Endpoint.c           \
@@ -453,7 +454,7 @@ ALL_ASFLAGS = -mmcu=$(MCU) -I. -x assembler-with-cpp $(ASFLAGS)
 
 
 # Default target.
-all: begin settings.sig.h gccversion sizebefore build sizeafter end
+all: begin gccversion builddirs sizebefore build sizeafter end
 
 # Change the build target to build a HEX file or a library.
 build: elf hex eep list sym
@@ -488,6 +489,9 @@ ELFSIZE = $(SIZE) $(MCU_FLAG) $(FORMAT_FLAG) $(TARGET).elf
 MCU_FLAG = $(shell $(SIZE) --help | grep -- --mcu > /dev/null && echo --mcu=$(MCU) )
 FORMAT_FLAG = $(shell $(SIZE) --help | grep -- --format=.*avr > /dev/null && echo --format=avr )
 
+builddirs:
+	@-mkdir -p $(foreach D, $(OBJ), \
+			$(shell dirname $(D)) )
 
 sizebefore:
 	@if test -f $(TARGET).elf; then echo; echo $(MSG_SIZE_BEFORE); $(ELFSIZE); \
@@ -680,7 +684,7 @@ clean_list :
 	$(REMOVE) $(TARGET).map
 	$(REMOVE) $(TARGET).sym
 	$(REMOVE) $(TARGET).list
-	$(REMOVE) $(SRC:%.c=$(OBJDIR)/%.o) settings.sig.h
+	$(REMOVE) $(SRC:%.c=$(OBJDIR)/%.o)
 	$(REMOVE) $(SRC:%.c=$(OBJDIR)/%.lst)
 	$(REMOVE) $(SRC:.c=.s)
 	$(REMOVE) $(SRC:.c=.d)
@@ -707,4 +711,4 @@ $(shell mkdir $(OBJDIR) 2>/dev/null)
 .PHONY : all begin finish end sizebefore sizeafter gccversion \
 build elf hex eep list sym coff extcoff doxygen clean          \
 clean_list clean_doxygen program dfu flip flip-ee dfu-ee      \
-debug gdb-config
+debug gdb-config builddirs