boot: zephyr: add config for swap without scratch

Add Zephyr option to enable building a bootloader that uses an
alternative swap algorithm, that first moves up all sectors in slot1 and
then directly swaps between slot0 and slot1.

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/boot/zephyr/CMakeLists.txt b/boot/zephyr/CMakeLists.txt
index f559844..5f21aea 100644
--- a/boot/zephyr/CMakeLists.txt
+++ b/boot/zephyr/CMakeLists.txt
@@ -92,6 +92,9 @@
 zephyr_library_include_directories(${BOOT_DIR}/bootutil/include)
 zephyr_library_sources(
   ${BOOT_DIR}/bootutil/src/loader.c
+  ${BOOT_DIR}/bootutil/src/swap_misc.c
+  ${BOOT_DIR}/bootutil/src/swap_scratch.c
+  ${BOOT_DIR}/bootutil/src/swap_move.c
   ${BOOT_DIR}/bootutil/src/bootutil_misc.c
   ${BOOT_DIR}/bootutil/src/image_validate.c
   ${BOOT_DIR}/bootutil/src/encrypted.c