boot: bootutil: loader: Let image version comparison use build number

Change allows using build number in image version comparison.

Signed-off-by: Marek Pieta <Marek.Pieta@nordicsemi.no>
diff --git a/boot/zephyr/Kconfig b/boot/zephyr/Kconfig
index b232110..1493dc3 100644
--- a/boot/zephyr/Kconfig
+++ b/boot/zephyr/Kconfig
@@ -522,6 +522,15 @@
 	help
 	  Enables support of multi image update.
 
+config BOOT_VERSION_CMP_USE_BUILD_NUMBER
+	bool "Use build number while comparing image version"
+	depends on (UPDATEABLE_IMAGE_NUMBER > 1) || BOOT_DIRECT_XIP || \
+		   BOOT_RAM_LOAD || MCUBOOT_DOWNGRADE_PREVENTION
+	help
+	  By default, the image version comparison relies only on version major,
+	  minor and revision. Enable this option to take into account the build
+	  number as well.
+
 choice BOOT_DOWNGRADE_PREVENTION_CHOICE
 	prompt "Downgrade prevention"
 	optional
diff --git a/boot/zephyr/include/mcuboot_config/mcuboot_config.h b/boot/zephyr/include/mcuboot_config/mcuboot_config.h
index a235e15..e14bf4c 100644
--- a/boot/zephyr/include/mcuboot_config/mcuboot_config.h
+++ b/boot/zephyr/include/mcuboot_config/mcuboot_config.h
@@ -93,6 +93,10 @@
 #define MCUBOOT_IMAGE_NUMBER    1
 #endif
 
+#ifdef CONFIG_BOOT_VERSION_CMP_USE_BUILD_NUMBER
+#define MCUBOOT_VERSION_CMP_USE_BUILD_NUMBER
+#endif
+
 #ifdef CONFIG_BOOT_SWAP_SAVE_ENCTLV
 #define MCUBOOT_SWAP_SAVE_ENCTLV 1
 #endif