lg2: commit: add support for journal-only method

The design document for the new event system references an
option to log events to the journal rather than to dbus[1] using
the 'OPENBMC_MESSAGE_ID' identifier.  Add support and test cases
for this as a meson option.

[1]: https://github.com/openbmc/docs/blob/master/designs/event-logging.md#phosphor-logging

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6cb94453c6cc95a9ccbbbc11859b70ef12d375fd
diff --git a/config/config.h.meson b/config/config.h.meson
index 698b09d..f852bab 100644
--- a/config/config.h.meson
+++ b/config/config.h.meson
@@ -36,4 +36,7 @@
 static constexpr auto FIRST_CEREAL_CLASS_VERSION_WITH_RESOLUTION = "5";
 static constexpr size_t CLASS_VERSION = 5;
 
+static constexpr bool LG2_COMMIT_DBUS = @lg2_commit_dbus@;
+static constexpr bool LG2_COMMIT_JOURNAL = @lg2_commit_journal@;
+
 // vim: ft=cpp