Use unified build for Platform, PluginProcess, and StorageProcess
These are so small, they can be handled together.
FWIW Platform is unified now for Cocoa ports.
(In reply to Tim Horton from comment #1)
> FWIW Platform is unified now for Cocoa ports.
PluginProcess probably won't be possible until GTK port gets rid of WebKitPluginProcess2 (a secondary plugin process built against GTK+ 2, to ensure Flash isn't loaded into a GTK+ 3 process), since I've failed to figure out how to make it link (honestly not even sure what's wrong) and it's only a small number of files so probably not worth worrying about. (Hopefully we can remove WebKitPluginProcess2 after a couple years, anyway.) So just StorageProcess remains for now.