build: Add wrapfiles for dependencies

Update meson.build and add wrapfiles so that all dependencies are
handled as subprojects.

This allows builds completely outside of bitbake or an SDK.

Tested: built phosphor-debug-collector repo successfully using
        `meson -Dtests build`.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I51bae90f4fac113270e259b7acac3630b5ec6778
diff --git a/subprojects/phosphor-logging.wrap b/subprojects/phosphor-logging.wrap
new file mode 100644
index 0000000..a039fcf
--- /dev/null
+++ b/subprojects/phosphor-logging.wrap
@@ -0,0 +1,3 @@
+[wrap-git]
+url = https://github.com/openbmc/phosphor-logging.git
+revision = HEAD