Adding the PCH file. Maybe this fixes the build?

git-svn-id: http://svn.igniterealtime.org/svn/repos/wildfire/trunk@6482 b35dd754-fafc-0310-a699-88a17e54d16e

build/osx/wildfirePrefPane/wildfirePrefPane_Prefix.pch

+//
+// Prefix header for all source files of the 'wildfirePrefPane' target in the 'wildfirePrefPane' project.
+//
+
+#ifdef __OBJC__
+    #import <Foundation/Foundation.h>
+    #import <AppKit/AppKit.h>
+#endif