um: Define PTRACE_OLDSETOPTIONS

...such that processes within UML can do a ptrace(PTRACE_OLDSETOPTIONS, ...)
Signed-off-by: NRichard Weinberger <richard@nod.at>

arch/um/include/asm/ptrace-generic.h

@@ -27,6 +27,8 @@ struct pt_regs {
 
 #define instruction_pointer(regs) PT_REGS_IP(regs)
 
+#define PTRACE_OLDSETOPTIONS 21
+
 struct task_struct;
 
 extern long subarch_ptrace(struct task_struct *child, long request,