fix(build_multi_image): Add size check for epicardium binary

The linker should already catch this case and error out early but just
to be absolutely sure, add a second check here so we don't get an
unexpectedly large epicardium binary which would overlap into pycardium
storage.

Signed-off-by: Rahix <rahix@rahix.de>

bootloader/build_multi_image.sh

@@ -6,6 +6,11 @@ BIN1="$2"
 BIN2="$3"
 BINOUT="$4"
 
+if [ "$(stat -c "%s" "${BIN1}")" -gt 458752 ]; then
+    echo "$0: ${BIN1} is too big to fit!" >&2
+    exit 1
+fi
+
 objcopy -I binary -O binary --pad-to=458752 --gap-fill=255 "${BIN1}" "$BINOUT"
 cat "$BIN2" >>"$BINOUT"