build: add support for meson

Mostly a direct port from the current autotools implementation, except
configurability for several variables is dropped because they are
unused:

SOFTWARE_OBJPATH, IMG_DIR, MANIFEST_FILE, PUBLICKEY_FILE_NAME,
HASH_FILE_NAME, PNOR_SIGNED_IMAGE_CONF_PATH, SIGNATURE_FILE_EXT,
ACTIVE_PNOR_MAX_ALLOWED, PNOR_VERSION_PARTITION

Change-Id: I3929518b786600435ae48484f63633c52a65d1f9
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meson_options.txt b/meson_options.txt
new file mode 100644
index 0000000..c6a640a
--- /dev/null
+++ b/meson_options.txt
@@ -0,0 +1,5 @@
+option('tests', type: 'feature', description: 'Build tests.')
+option('device-type', type: 'combo', choices: ['static', 'ubi', 'mmc'], description: 'Select which device type to support')
+option('vpnor', type: 'feature', description: 'Enable virtual PNOR support')
+option('verify-signature', type: 'feature', description: 'Enable image signature validation')
+option('msl', type: 'string', description: 'Minimum Ship Level')