Fix compiler warnings

Fix compiler warnings

src/shell-global.c src/shell-process.c: Remove dead code
src/shell-texture-cache.c src/shell-status-menu.c: Remove
  <foo>_new() functions that weren't in the header file and
  not used anyways:
src/shell-texture-cache.[ch]: Fix a prototype that used ()
  when (void) was intended.

http://bugzilla.gnome.org/show_bug.cgi?id=590998