build_haiku_image: don't recreate indices when updating

mkinex fails when the indices already exist.

build/scripts/build_haiku_image

@@ -292,6 +292,7 @@ if [ -n "$updateAllPackages" ]; then
 	$mkdir -p "${tPrefix}system/packages"
 fi
 
+if [ ! $updateOnly ]; then
 echo "Creating filesystem indices..."
 	$mkindex -t string Audio:Album
 	$mkindex -t string Audio:Artist
@@ -331,6 +332,7 @@ $mkindex -t int32 Media:Year
 	$mkindex -t int32 MAIL:account_id
 	$mkindex -t int32 MAIL:read
 	$mkindex -t int32 MAIL:when
+fi
 
 echo "Populating image ..."
 while [ $# -gt 0 ]; do