Support for identification of source Streams.

We identify uniquelly a given source Stream by a triple of numbers: the
filesystem id, the device id inside the filesystem, and the inode id.

src/fsource.c

@@ -9,6 +9,11 @@
 #include "fsource.h"
 #include <stdlib.h>
 
+/**
+ * Values belong 100 are reserved for out own usage
+ */
+unsigned int iso_fs_global_id = 100;
+
 void iso_file_source_ref(IsoFileSource *src)
 {
 	++src->refcount;