log-manager: enable non-standard path for local tests

Enable the log-manager to be launched with a path other than
`/var/phosphor-logging` to allow it to be ran on a development system
for test purposes.  This required some refactoring throughout as to
how paths were handled.

Tested:

After running tests, `/tmp/phosphor-logging` is populated with
entries.  Launching `./builddir/phosphor-log-manager
/tmp/phosphor-logging`, the log-manager will have the entries on
dbus:

```
$ busctl --user tree xyz.openbmc_project.Logging
└─ /xyz
  └─ /xyz/openbmc_project
    └─ /xyz/openbmc_project/logging
      ├─ /xyz/openbmc_project/logging/entry
      │ ├─ /xyz/openbmc_project/logging/entry/100
      │ ├─ /xyz/openbmc_project/logging/entry/101
      │ ├─ /xyz/openbmc_project/logging/entry/102
      │ ├─ /xyz/openbmc_project/logging/entry/103
```

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I84968edeed0dcf73aaf8bb653060b6d3400b9b7b
diff --git a/extensions/openpower-pels/tools/peltool.cpp b/extensions/openpower-pels/tools/peltool.cpp
index 85fe9d1..810223a 100644
--- a/extensions/openpower-pels/tools/peltool.cpp
+++ b/extensions/openpower-pels/tools/peltool.cpp
@@ -65,7 +65,7 @@
 
 std::string pelLogDir()
 {
-    return std::string(EXTENSION_PERSIST_DIR) + "/pels/logs";
+    return std::string(phosphor::logging::paths::extension()) + "/pels/logs";
 }
 
 /**