Clean up DOXYGEN and SOURCES build system modules - use non-recursively evaluated make variables.

LUFA/Build/lufa.doxygen.in

@@ -66,11 +66,11 @@ $(call ERROR_IF_NONBOOL, DOXYGEN_FAIL_ON_WARNING)
 MSG_DOXYGEN_CMD         := ' [DOXYGEN] :'
 
 # Determine Doxygen invocation command
-BASE_DOXYGEN_CMD = ( cat $(DOXYGEN_CONF) $(DOXYGEN_OVERRIDE_PARAMS:%=; echo "%") ) | doxygen -
+BASE_DOXYGEN_CMD := ( cat $(DOXYGEN_CONF) $(DOXYGEN_OVERRIDE_PARAMS:%=; echo "%") ) | doxygen -
 ifeq ($(DOXYGEN_FAIL_ON_WARNING), Y)
-   DOXYGEN_CMD = if ( $(BASE_DOXYGEN_CMD) 2>&1 | grep -v "warning: ignoring unsupported tag" ;); then exit 1; fi;
+   DOXYGEN_CMD := if ( $(BASE_DOXYGEN_CMD) 2>&1 | grep -v "warning: ignoring unsupported tag" ;); then exit 1; fi;
 else
-   DOXYGEN_CMD = $(BASE_DOXYGEN_CMD)
+   DOXYGEN_CMD := $(BASE_DOXYGEN_CMD)
 endif
 
 doxygen:

LUFA/Build/lufa.sources.in

@@ -67,7 +67,7 @@ $(call ERROR_IF_EMPTY, ARCH)
 LUFA_ROOT_PATH ?= $(patsubst %/,%,$(LUFA_PATH))
 
 # Construct LUFA module source variables
-LUFA_SRC_USB         = $(LUFA_ROOT_PATH)/Drivers/USB/Core/$(ARCH)/Device_$(ARCH).c          \
+LUFA_SRC_USB         := $(LUFA_ROOT_PATH)/Drivers/USB/Core/$(ARCH)/Device_$(ARCH).c          \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Core/$(ARCH)/Endpoint_$(ARCH).c        \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Core/$(ARCH)/Host_$(ARCH).c            \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Core/$(ARCH)/Pipe_$(ARCH).c            \
@@ -81,7 +81,7 @@ LUFA_SRC_USB         = $(LUFA_ROOT_PATH)/Drivers/USB/Core/$(ARCH)/Device_$(ARCH)
                         $(LUFA_ROOT_PATH)/Drivers/USB/Core/HostStandardReq.c                 \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Core/USBTask.c                         \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Class/Common/HIDParser.c
-LUFA_SRC_USBCLASS    = $(LUFA_ROOT_PATH)/Drivers/USB/Class/Device/AudioClassDevice.c        \
+LUFA_SRC_USBCLASS    := $(LUFA_ROOT_PATH)/Drivers/USB/Class/Device/AudioClassDevice.c        \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Class/Device/CDCClassDevice.c          \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Class/Device/HIDClassDevice.c          \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Class/Device/MassStorageClassDevice.c  \
@@ -96,18 +96,18 @@ LUFA_SRC_USBCLASS    = $(LUFA_ROOT_PATH)/Drivers/USB/Class/Device/AudioClassDevi
                         $(LUFA_ROOT_PATH)/Drivers/USB/Class/Host/PrinterClassHost.c          \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Class/Host/RNDISClassHost.c            \
                         $(LUFA_ROOT_PATH)/Drivers/USB/Class/Host/StillImageClassHost.c
-LUFA_SRC_TEMPERATURE = $(LUFA_ROOT_PATH)/Drivers/Board/Temperature.c
-LUFA_SRC_SERIAL      = $(LUFA_ROOT_PATH)/Drivers/Peripheral/$(ARCH)/Serial_$(ARCH).c
-LUFA_SRC_TWI         = $(LUFA_ROOT_PATH)/Drivers/Peripheral/$(ARCH)/TWI_$(ARCH).c
+LUFA_SRC_TEMPERATURE := $(LUFA_ROOT_PATH)/Drivers/Board/Temperature.c
+LUFA_SRC_SERIAL      := $(LUFA_ROOT_PATH)/Drivers/Peripheral/$(ARCH)/Serial_$(ARCH).c
+LUFA_SRC_TWI         := $(LUFA_ROOT_PATH)/Drivers/Peripheral/$(ARCH)/TWI_$(ARCH).c
 
 ifeq ($(ARCH), UC3)
-   LUFA_SRC_PLATFORM = $(LUFA_PATH)/Platform/UC3/Exception.S $(LUFA_PATH)/Platform/UC3/InterruptManagement.c
+   LUFA_SRC_PLATFORM := $(LUFA_PATH)/Platform/UC3/Exception.S $(LUFA_PATH)/Platform/UC3/InterruptManagement.c
 else
-   LUFA_SRC_PLATFORM =
+   LUFA_SRC_PLATFORM :=
 endif
 
 # Build a list of all available module sources
-LUFA_SRC_ALL_FILES   = $(LUFA_SRC_USB)            \
+LUFA_SRC_ALL_FILES   := $(LUFA_SRC_USB)            \
                         $(LUFA_SRC_USBCLASS)       \
                         $(LUFA_SRC_TEMPERATURE)    \
                         $(LUFA_SRC_SERIAL)         \