Don't reconstruct the ps file from the PDF, this makes ghostscript shit itself:
GPL Ghostscript 9.04: Error: Font Renderer Plugin ( FreeType ) return code = -1

Index: doc/makefile.in
--- doc/makefile.in.orig
+++ doc/makefile.in
@@ -99,7 +99,7 @@ core-pre:
 
 core-post:
 
-doc: info pdf html txt ps
+doc: info pdf html txt
 
 info: gambit.info