shill: Remove GLibInterface and mock out GLib directly.

The interface didn't provide any useful abstraction in this case.

BUG=chromium-os:16899
TEST=unit tests

Change-Id: I76fcdd757ab7c20e1904ac025dcf218f6eba50cc
Reviewed-on: http://gerrit.chromium.org/gerrit/3104
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Chris Masone <cmasone@chromium.org>
diff --git a/glib.cc b/glib.cc
index bf1cda7..13545ac 100644
--- a/glib.cc
+++ b/glib.cc
@@ -6,6 +6,8 @@
 
 namespace shill {
 
+GLib::~GLib() {}
+
 guint GLib::ChildWatchAdd(GPid pid,
                           GChildWatchFunc function,
                           gpointer data) {