regulators: Create journal interface

Create a light-weight interface for logging messages to the systemd
journal.

The standard interface implementation calls the phosphor-logging
functions to create real journal entries.  This is the implementation
that the phosphor-regulators application links with.

The mock interface implementation stores the journal messages in static
vectors and provides functions to access them.  This is the
implementation that testcases link with.

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: I5421794f7402f999b65c8367db5dd5ba07110f4a
diff --git a/phosphor-regulators/src/meson.build b/phosphor-regulators/src/meson.build
index ef40cb9..3caa543 100644
--- a/phosphor-regulators/src/meson.build
+++ b/phosphor-regulators/src/meson.build
@@ -30,11 +30,13 @@
 
 phosphor_regulators = executable(
     'phosphor-regulators',
+    'journal.cpp',
     'main.cpp',
     dependencies: [
+        libi2c_dep,
+        phosphor_logging,
         sdbusplus,
-        sdeventplus,
-        libi2c_dep
+        sdeventplus
     ],
     link_with: phosphor_regulators_library,
     implicit_include_directories: false,