Added some macros and an error message if another compiler than GCC is used.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24872 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/BeBuild.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2007, Haiku, Inc. All Rights Reserved.
+ * Copyright 2007-2008, Haiku, Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  */
 #ifndef _BE_BUILD_H
@@ -21,6 +21,11 @@
 #	define _PRINTFLIKE(_format_, _args_) \
 		__attribute__((format(__printf__, _format_, _args_)))
 #	define _EXPORT
+#else
+#	define _UNUSED(argument) argument
+#	error Define _PACKED for your compiler
+#	define _PRINTFLIKE(format, args)
+#	define _EXPORT
 #endif
 
 #endif	/* _BE_BUILD_H */