profiler: extract SpProfiler into an interface

It would be nice to be able to support a remote profiler session in the
future, so add SpLocalProfiler implementation of SpProfiler interface.

lib/sp-local-profiler.h

@@ -0,0 +1,40 @@
+/* sp-local-profiler.h
+ *
+ * Copyright (C) 2016 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef SP_LOCAL_PROFILER_H
+#define SP_LOCAL_PROFILER_H
+
+#include "sp-profiler.h"
+
+G_BEGIN_DECLS
+
+#define SP_TYPE_LOCAL_PROFILER (sp_local_profiler_get_type())
+
+G_DECLARE_DERIVABLE_TYPE (SpLocalProfiler, sp_local_profiler, SP, LOCAL_PROFILER, GObject)
+
+struct _SpLocalProfilerClass
+{
+  GObjectClass parent_class;
+  gpointer     padding[8];
+};
+
+SpProfiler *sp_local_profiler_new (void);
+
+G_END_DECLS
+
+#endif /* SP_LOCAL_PROFILER_H */