* At least the Darwin linker doesn't like double symbols during the
  final linking stage...

--- a/jpeg/jpegconf.h
+++ b/jpeg/jpegconf.h
@@ -27,6 +27,6 @@
 #   pragma warning(disable : 4244)
 #   pragma warning(disable : 4142)
 #else
-#   define JPEGEXPORT
-#   define FPXEXPORT
+#   define JPEGEXPORT extern
+#   define FPXEXPORT extern
 #endif