renumber PTRACE_EVENT_STOP so that future PTRACE_O_TRACEfoo

PTRACE_EVENT_foo and PTRACE_O_TRACEfoo used to match.

New PTRACE_EVENT_STOP is the first event which has no corresponding PTRACE_O_TRACE option. If we will ever want to add another such option, its PTRACE_EVENT's value will collide with PTRACE_EVENT_STOP's value.

This patch changes PTRACE_EVENT_STOP value to prevent this.

While at it, added comment - the one above, "Wait extended result codes for the above trace options", is not true for PTRACE_EVENT_STOP.

vda

index 800f113..1729c00 100644
@@ -72,7 +72,8 @@
 #define PTRACE_EVENT_EXEC	4
 #define PTRACE_EVENT_VFORK_DONE	5
 #define PTRACE_EVENT_EXIT	6
-#define PTRACE_EVENT_STOP	7
+/* Extended result codes which aren't enabled by options.  */
+#define PTRACE_EVENT_STOP	128
 
 #include <asm/ptrace.h>