[LyX/master] Initialize definition_ correctly

[Georg Baum]

commit af6cb2d0e239a4e84a8e25c947862c215aac93f4
Author: Georg Baum <b...@lyx.org>
Date:   Mon Mar 30 22:04:52 2015 +0200

    Initialize definition_ correctly

diff --git a/src/mathed/MathMacro.cpp b/src/mathed/MathMacro.cpp
index b23be09..4cdecbd 100644
--- a/src/mathed/MathMacro.cpp
+++ b/src/mathed/MathMacro.cpp
@@ -136,7 +136,8 @@ private:
 
 MathMacro::MathMacro(Buffer * buf, docstring const & name)
        : InsetMathNest(buf, 0), name_(name), displayMode_(DISPLAY_INIT),
-               expanded_(buf), attachedArgsNum_(0), optionals_(0), 
nextFoldMode_(true),
+               expanded_(buf), definition_(buf), attachedArgsNum_(0),
+               optionals_(0), nextFoldMode_(true),
                macroBackup_(buf), macro_(0), needsUpdate_(false),
                isUpdating_(false), appetite_(9)
 {}