Fix remaining bugs with the CPC ROM version.

- Fix an extra const for the icons that shouldn't be there for the ROM
  version. It is there in the loadable version of the DSC files to
  workaround linker script limitations, but in the ROM it results in
  trying to write to ROM when the icons are added to the desktop
- Fix a bug (broken code generation by the compiler?) that leads to
  vertical lines in windows not stopping where they should and going all
  the way down the screen (clipping was applied when it shouldn't,
  leading to an overflow)
diff --git a/contiki-cpc/Makefile.cpc b/contiki-cpc/Makefile.cpc
index d2b3c68..2b47311 100644
--- a/contiki-cpc/Makefile.cpc
+++ b/contiki-cpc/Makefile.cpc
@@ -38,7 +38,7 @@
 include Makefile.common
 
 CFLAGS:=$(CFLAGSCOMMON) --compile-only \
-        -DWITH_ASCII \
+	-DWITH_ASCII -DBUILDING_FOR_ROM=1 \
 	-DWITH_LOADER_ARCH=1
 
 UIP_OBJ = ../contiki/uip/dhcpc.o \
@@ -105,4 +105,6 @@
 	makebin -p -s 65536 -o 0xC000 < contiki.ihx > contiki.bin
 	cpcfs contiki.dsk f
 	cpcfs contiki.dsk p contiki.bin,256,256 -b -e
+	# Delete directory.dsc so it is rebuilt for the "programs" build with different defines
+	rm -f apps/directory-dsc.o ../contiki/apps/processes-dsc.o