meson: add subproject wrap files

The repository isn't buildable in a meson wrapfile mode without two
missing dependencies: phosphor-dbus-interfaces and sdbusplus.  Add wrap
files for both of them.

Change-Id: Idec177b8a7b08a665aa03d353122055b7edc157e
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/subprojects/sdbusplus.wrap b/subprojects/sdbusplus.wrap
new file mode 100644
index 0000000..edd9a31
--- /dev/null
+++ b/subprojects/sdbusplus.wrap
@@ -0,0 +1,7 @@
+[wrap-git]
+url = https://github.com/openbmc/sdbusplus.git
+revision = HEAD
+
+[provide]
+sdbusplus = sdbusplus_dep
+program_names = sdbus++, sdbus++-gen-meson