HOTFIX: simplify symbol names going into the ROMFS object, hopefully this avoids inconsistent symbol naming on Windows.

makefiles/firmware.mk

@@ -280,7 +280,7 @@ ifeq ($(ROMFS_FILES),)
 $(error ROMFS_ROOT $(ROMFS_ROOT) specifies a directory containing no files)
 endif
 ROMFS_DEPS		+= $(ROMFS_FILES)
-ROMFS_IMG		 = $(WORK_DIR)romfs.img
+ROMFS_IMG		 = romfs.img
 ROMFS_CSRC		 = $(ROMFS_IMG:.img=.c)
 ROMFS_OBJ		 = $(ROMFS_CSRC:.c=.o)
 LIBS			+= $(ROMFS_OBJ)

makefiles/toolchain_gnu-arm-eabi.mk

@@ -254,6 +254,20 @@ endef
 # - relink the object and insert the binary file
 # - edit symbol names to suit
 #
+# NOTE: exercise caution using this with absolute pathnames; it looks
+#       like the MinGW tools insert an extra _ in the binary symbol name; e.g.
+#	the path:
+#
+#	/d/px4/firmware/Build/px4fmu_default.build/romfs.img
+#
+#	is assigned symbols like:
+#
+#	_binary_d__px4_firmware_Build_px4fmu_default_build_romfs_img_size
+#
+#	when we would expect
+#
+#	_binary__d_px4_firmware_Build_px4fmu_default_build_romfs_img_size
+#
 define BIN_SYM_PREFIX
 	_binary_$(subst /,_,$(subst .,_,$1))
 endef
@@ -267,4 +281,5 @@ define BIN_TO_OBJ
 		--redefine-sym $(call BIN_SYM_PREFIX,$1)_start=$3 \
 		--redefine-sym $(call BIN_SYM_PREFIX,$1)_size=$3_len \
 		--strip-symbol $(call BIN_SYM_PREFIX,$1)_end
+	$(Q) $(REMOVE) $2.c $2.c.o
 endef