Add format printf attribute to panic() prototype and fix the error

this catches.

Signed-off-by: Jimi Xenidis <jimix@watson.ibm.com>
Signed-off-by: Keir Fraser <keir@xensource.com>

xen/arch/x86/traps.c

@@ -705,7 +705,7 @@ asmlinkage int do_page_fault(struct cpu_user_regs *regs)
         panic("CPU%d FATAL PAGE FAULT\n"
               "[error_code=%04x]\n"
               "Faulting linear address: %p\n",
-              smp_processor_id(), regs->error_code, addr);
+              smp_processor_id(), regs->error_code, _p(addr));
     }
 
     propagate_page_fault(addr, regs->error_code);

xen/include/xen/lib.h

@@ -47,7 +47,8 @@ extern void debugtrace_printk(const char *fmt, ...);
 #define printk(_f , _a...) printf( _f , ## _a )
 extern void printf(const char *format, ...)
     __attribute__ ((format (printf, 1, 2)));
-extern void panic(const char *format, ...);
+extern void panic(const char *format, ...)
+    __attribute__ ((format (printf, 1, 2)));
 extern long vm_assist(struct domain *, unsigned int, unsigned int);
 
 /* vsprintf.c */