Do not clean resource header files

Customisations are needed to pull in <types.h> which will be committed.

Makefile

@@ -3,6 +3,8 @@ MAKE=make
 
 all: release out/rom.s test
 
+release: res/samples
+
 include $(SGDK)/makefile.gen
 
 EXTRA_FLAGS:=-DMODULE_MEGAWIFI=1 \
@@ -17,16 +19,20 @@ else
 	LTO_FLAGS:=-flto
 endif
 
-release: FLAGS= $(DEFAULT_FLAGS) -O3 -fuse-linker-plugin -fno-web -fno-gcse \
-	-fno-unit-at-a-time -fomit-frame-pointer $(LTO_FLAGS)
-release: LIBMD= $(LIB)/libmd.a
-release: res/samples pre-build out/rom.bin out/symbol.txt
-
 res/samples:
-	wget "https://github.com/rhargreaves/mega-drive-pcm-samples/releases/download/v1/samples.zip" -O temp.zip
+	wget "https://github.com/rhargreaves/mega-drive-pcm-samples/releases/download/v1/samples.zip" \
+		-O temp.zip
 	unzip temp.zip -d res/samples
 	rm temp.zip
 
+cleanres: cleantmp
+	$(RM) -f $(RES_DEP) $(RES_DEPS)
+
+release: FLAGS= $(DEFAULT_FLAGS) -O3 -fuse-linker-plugin -fno-web -fno-gcse \
+	-fno-unit-at-a-time -fomit-frame-pointer $(LTO_FLAGS)
+release: LIBMD= $(LIB)/libmd.a
+release: pre-build out/rom.bin out/symbol.txt
+
 out/rom.s: out/rom.out
 	m68k-elf-objdump -S $^ > $@