Implement delay injection

Implement delay injection

Add -e inject=SET:delay_enter= and -e inject=SET:delay_exit= options.

* configure.ac (AC_SEARCH_LIBS): Check for timer_create -lrt.
* delay.c: New file.
* Makefile.am (strace_SOURCES): Add it.
(strace_LDADD): Add $(timer_LIBS).
* defs.h (INJECT_F_DELAY_ENTER, INJECT_F_DELAY_EXIT,
TCB_INJECT_DELAY_EXIT, TCB_DELAYED, inject_delay_exit, syscall_delayed):
New macros.
(alloc_delay_data, fill_delay_data, is_delay_timer_created,
arm_delay_timer, delay_tcb): New prototypes.
(struct inject_data): Replace reserved field with delay_idx.
(struct tcb): Add delay_expiration_time field.
* filter_qualify.c (parse_delay_token): New function.
(parse_inject_token): Use it.
(qualify_inject_common): Initialize struct inject_opts.data.delay_idx.
* strace.c: Include <setjmp.h>
(timer_jmp_buf, timer_set): New static variables.
(timer_sighandler, restart_delayed_tcb, restart_delayed_tcbs): New
functions.
(init): Block SIGALRM, set SIGALRM handler.
(dispatch_event): Do not restart delayed syscalls.
(next_event): Unblock SIGALRM during wait4 invocation.
* syscall.c (tamper_with_syscall_entering): Arm delay timer if
INJECT_F_DELAY_ENTER injection flag is set, set TCB_INJECT_DELAY_EXIT
flag if INJECT_F_DELAY_EXIT injection flag is set.
tamper_with_syscall_exiting): Arm delay timer if inject_delay_exit.
(syscall_exiting_trace): Call tamper_with_syscall_exiting in case of
inject_delay_exit.
(syscall_exiting_finish): Clear TCB_INJECT_DELAY_EXIT flag.
* strace.1.in: Document delay injection.
* NEWS: Mention this improvement.

Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>