Don't set stretchable spacers size to 0, this doesn't work so use 1 instead.

Don't set stretchable spacers size to 0, this doesn't work so use 1 instead.

If the toolbar is not big enough for its fixed-size contents, we set the size
of the tools corresponding to stretchable spacers to 0 but this didn't really
work and resulted in bad toolbar appearance even after resizing it to be big
enough (as could be seen in samples/xrc).

So set the spacers size to at least 1 to ensure that we do resize them
correctly.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63173 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775