gtk/deprecated/gtkstatusicon.c: Fix Build on C89 Compilers

Declare variable at the top of the block, which is needed from the change
in commit 1bad7865.
Fix Up Visual Studio Property Sheets

"Install" gdkbroadwaydisplay.h, as it is a public header of GDK Broadway,
also fix the MSVC 2010+ gtk-copy-gdk-broadway.props property sheet as a
'>' is missing.  Sorry for not noting these issues earlier, as MSVC
Broadway builds were recently restored.  My bad :|