Rename mis->file to from_src_file

'file' becomes confusing when you have flows in each direction;
rename to make it clear.
This leaves just the main forward direction ms->file, which is used
in a lot of places and is probably not worth renaming given the churn.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 8334621..83fba23 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -48,7 +48,7 @@
 
 /* State for the incoming migration */
 struct MigrationIncomingState {
-    QEMUFile *file;
+    QEMUFile *from_src_file;
 
     /* See savevm.c */
     LoadStateEntry_Head loadvm_handlers;