libxc: disable xc_ptrace on x86 Linux

It has been unused since 21732:eb34666befcc.

Removing the include of sys/ptrace.h and threaddb.h exposed a few
places which were using time(2) or gettimeofday(2) without including
time.h or sys/time.h respectively and were relying on an include.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/python/xen/lowlevel/checkpoint/libcheckpoint.c

@@ -4,7 +4,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <time.h>
+#include <sys/time.h>
 #include <signal.h>
 #include <sys/stat.h>
 #include <unistd.h>