uml: fix build for !CONFIG_PRINTK

Handle the case of CONFIG_PRINTK being disabled.  This requires a do-nothing
stub to be present in arch/um/include/user.h so that we don't get references
to printk from libc code.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/include/user.h

 /* 
- * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
 
 #ifndef __USER_H__
 #define __USER_H__
 
+#include "uml-config.h"
+
 /*
  * The usual definition - copied here because the kernel provides its own,
  * fancier, type-safe, definition.  Using that one would require
@@ -23,8 +25,17 @@
 
 extern void panic(const char *fmt, ...)
 	__attribute__ ((format (printf, 1, 2)));
+
+#ifdef UML_CONFIG_PRINTK
 extern int printk(const char *fmt, ...)
 	__attribute__ ((format (printf, 1, 2)));
+#else
+static inline int printk(const char *fmt, ...)
+{
+	return 0;
+}
+#endif
+
 extern void schedule(void);
 extern int in_aton(char *str);
 extern int open_gdb_chan(void);