kernel/debug: Introduce arch_debug_snooze() and make use of it.

The idea is to add a facility that will use less CPU than
the loops we currently use. The default implementation just
calls spin(), which is rdtsc+pause. This already may save
some power compared to what we previously did, which was to
re-check serial ports, PS/2, etc. every single loop in
the debugger, broken up only by "pause".

Change-Id: Ie421adae5c25ad6ae0c266d1d28c2ea7b81ae465
Reviewed-on: https://review.haiku-os.org/c/haiku/+/9603
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: waddlesplash <[email protected]>

headers/private/kernel/arch/debug.h

@@ -53,6 +53,8 @@ status_t arch_get_debug_variable(const char* variableName, uint64* value);
 
 ssize_t arch_debug_gdb_get_registers(char* buffer, size_t bufferSize);
 
+void arch_debug_snooze(bigtime_t duration);
+
 #ifdef __cplusplus
 }
 #endif