build: Use global variables instead of macros for test features

We don't want the build to depend on recompiling objects for test
separately from other executables. We can tweak settings via global
variables instead.

Change-Id: Ifdd078c2e381848ca1789934a36731eb8ceaf8b1
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/config_main.h b/config_main.h
new file mode 100644
index 0000000..78c223e
--- /dev/null
+++ b/config_main.h
@@ -0,0 +1,5 @@
+#pragma once
+
+const char* ERRLOG_PERSIST_PATH = "/var/lib/phosphor-logging/errors";
+const char* EXTENSION_PERSIST_DIR = "/var/lib/phosphor-logging/extensions";
+const bool IS_UNIT_TEST = false;