Add the includes the precompiled header was supplying on macOS

A build without SLIC3R_PCH had never been tried on macOS. Three files
used what pchheader.hpp happened to include: LocalesUtils.cpp needs
<sstream> and <iomanip>, and the two dialogs need <wx/tooltip.h>. The
GTK port's headers and libstdc++ pull these in transitively, the Cocoa
port's headers and libc++ do not.

src/slic3r/GUI/PhysicalPrinterDialog.cpp

@@ -9,6 +9,7 @@
 #include <boost/regex.hpp>
 
 #include <wx/sizer.h>
+#include <wx/tooltip.h>
 #include <wx/stattext.h>
 #include <wx/textctrl.h>
 #include <wx/button.h>