exception: add errno

sdbusplus is going to start requiring the get_errno[1,2] function on
all exceptions.  Since the exception defined here is using the same
dbus error as one already in sd_bus, set the errno here to match:

  src/libsystemd/sd-bus/bus-error.c:
    SD_BUS_ERROR_MAP("org.freedesktop.DBus.Error.Failed", EACCES),

1. https://github.com/openbmc/sdbusplus/commit/b6f729d68d9edcd43fa236eee386b193a95588e7
2. https://gerrit.openbmc-project.xyz/c/openbmc/sdbusplus/+/46718

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I132fa29dfd10bbdcaab1895e2287c2ac89096270
diff --git a/include/Utils.hpp b/include/Utils.hpp
index 0aff148..7b50036 100644
--- a/include/Utils.hpp
+++ b/include/Utils.hpp
@@ -77,16 +77,21 @@
     const char* name() const noexcept override
     {
         return "org.freedesktop.DBus.Error.Failed";
-    };
+    }
     const char* description() const noexcept override
     {
         return "internal error";
-    };
+    }
     const char* what() const noexcept override
     {
         return "org.freedesktop.DBus.Error.Failed: "
                "internal error";
-    };
+    }
+
+    int get_errno() const noexcept override
+    {
+        return EACCES;
+    }
 };
 
 inline bool fwVersionIsSame(void)