compile fix for STLPort

[Georg Baum]

The attached is needed for compilation with STLPort. I wonder what header 
drags in <string> for other STL versions?
Could somebody please apply?


Thanks,
Georg

Index: src/Spacing.C
===================================================================
RCS file: /cvs/lyx/lyx-devel/src/Spacing.C,v
retrieving revision 1.33
diff -u -p -r1.33 Spacing.C
--- src/Spacing.C	2004/02/13 07:30:53	1.33
+++ src/Spacing.C	2004/02/15 09:30:27
@@ -10,6 +10,7 @@
  */
 
 #include <config.h>
+#include <string>
 
 #include "Spacing.h"