boot: mynewt: add ECIES-X25519 support

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/boot/bootutil/pkg.yml b/boot/bootutil/pkg.yml
index 3f114f3..531d6a2 100644
--- a/boot/bootutil/pkg.yml
+++ b/boot/bootutil/pkg.yml
@@ -53,3 +53,9 @@
     - "@mcuboot/ext/tinycrypt-sha512/lib"
     - "@mcuboot/ext/mbedtls-asn1"
     - "@mcuboot/ext/fiat"
+
+pkg.deps.BOOTUTIL_ENCRYPT_X25519:
+    - "@mcuboot/ext/tinycrypt/lib"
+    - "@mcuboot/ext/tinycrypt-sha512/lib"
+    - "@mcuboot/ext/mbedtls-asn1"
+    - "@mcuboot/ext/fiat"
diff --git a/boot/mynewt/mcuboot_config/include/mcuboot_config/mcuboot_config.h b/boot/mynewt/mcuboot_config/include/mcuboot_config/mcuboot_config.h
index d29ddc3..696f2e7 100644
--- a/boot/mynewt/mcuboot_config/include/mcuboot_config/mcuboot_config.h
+++ b/boot/mynewt/mcuboot_config/include/mcuboot_config/mcuboot_config.h
@@ -63,8 +63,11 @@
 #if MYNEWT_VAL(BOOTUTIL_ENCRYPT_EC256)
 #define MCUBOOT_ENCRYPT_EC256 1
 #endif
+#if MYNEWT_VAL(BOOTUTIL_ENCRYPT_X25519)
+#define MCUBOOT_ENCRYPT_X25519 1
+#endif
 #if MYNEWT_VAL(BOOTUTIL_ENCRYPT_RSA) || MYNEWT_VAL(BOOTUTIL_ENCRYPT_KW) || \
-    MYNEWT_VAL(BOOTUTIL_ENCRYPT_EC256)
+    MYNEWT_VAL(BOOTUTIL_ENCRYPT_EC256) || MYNEWT_VAL(BOOTUTIL_ENCRYPT_X25519)
 #define MCUBOOT_ENC_IMAGES 1
 #endif
 #if MYNEWT_VAL(BOOTUTIL_SWAP_USING_MOVE)
diff --git a/boot/mynewt/mcuboot_config/syscfg.yml b/boot/mynewt/mcuboot_config/syscfg.yml
index d51cd34..06e9768 100644
--- a/boot/mynewt/mcuboot_config/syscfg.yml
+++ b/boot/mynewt/mcuboot_config/syscfg.yml
@@ -49,6 +49,9 @@
     BOOTUTIL_ENCRYPT_EC256:
         description: 'Support for encrypted images using ECIES-P256.'
         value: 0
+    BOOTUTIL_ENCRYPT_X25519:
+        description: 'Support for encrypted images using ECIES-X25519.'
+        value: 0
     BOOTUTIL_USE_MBED_TLS:
         description: 'Use mbed TLS for crypto operations.'
         value: 1