init-repository: fixed src/3rdparty/v8 sometimes pointing at wrong SHA1

This script was doing a `git clone' for each submodule (so that we can
use local mirrors), then using `git submodule update' to ensure all the
submodules point to the right SHA1.

Since this wasn't done recursively, a clean clone and init-repository
would leave qtbase/src/3rdparty/v8 pointing at whatever SHA1 was set in
the HEAD of qtbase, which is wrong.  Fix it by doing the update
recursively.

Change-Id: Id183d0f983bfd59b2b9d0a8e160a906545219784
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@nokia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

init-repository

@@ -510,7 +510,7 @@ sub git_clone_all_submodules
         }
     }
 
-    $self->exe('git', 'submodule', 'update');
+    $self->exe('git', 'submodule', 'update', '--recursive');
 
     return;
 }