[LyX/master] Add missing breaks

[Jean-Marc]

commit 4e4b2e224e156c7267daa7c147f833c6eb489436
Author: Jean-Marc <lasgout...@lyx.org>
Date:   Sat Sep 12 19:58:15 2015 +0200

    Add missing breaks
    
    Coveity issues 23333, 23334 and 23348.

diff --git a/src/frontends/qt4/GuiAlert.cpp b/src/frontends/qt4/GuiAlert.cpp
index 14cce93..4c9b162 100644
--- a/src/frontends/qt4/GuiAlert.cpp
+++ b/src/frontends/qt4/GuiAlert.cpp
@@ -82,9 +82,9 @@ int doPrompt(docstring const & title0, docstring const & 
question,
 
                lyxerr << "Assuming answer is ";
                switch (default_button) {
-               case 0: lyxerr << b1 << endl;
-               case 1: lyxerr << b2 << endl;
-               case 2: lyxerr << b3 << endl;
+               case 0: lyxerr << b1 << endl; break;
+               case 1: lyxerr << b2 << endl; break;
+               case 2: lyxerr << b3 << endl; break;
                case 3: lyxerr << b4 << endl;
                }
                if (!use_gui)