Fixed the remaining errors.

new/unix/GNUmakeinc.mk

@@ -8,7 +8,9 @@ osCFILES = \
 osHFILES = \
 	unix/uipriv_unix.h
 
+# thanks ebassi in irc.gimp.net/#gtk+
 osCFLAGS = \
+	-D_UI_EXTERN='__attribute__((visibility("default"))) extern' \
 	-fvisibility=hidden \
 	`pkg-config --cflags gtk+-3.0`
 

new/unix/uipriv_unix.h

@@ -4,9 +4,6 @@
 #define GDK_VERSION_MIN_REQUIRED GDK_VERSION_3_4
 #define GDK_VERSION_MAX_ALLOWED GDK_VERSION_3_4
 #include <gtk/gtk.h>
-
-// thanks ebassi in irc.gimp.net/#gtk+
-#define _UI_EXTERN __attribute__((visibility("default"))) extern
 #include "../ui.h"
 #include "../ui_unix.h"
 #include "../uipriv.h"