test_kprobes: Fix implicit declaration error of test_kprobes

If KPROBES_SANITY_TEST and ARCH_CORRECT_STACKTRACE_ON_KRETPROBE is enabled, but
STACKTRACE is not set. Build failed as below:

lib/test_kprobes.c: In function ‘stacktrace_return_handler’:
lib/test_kprobes.c:228:8: error: implicit declaration of function ‘stack_trace_save’; did you mean ‘stacktrace_driver’? [-Werror=implicit-function-declaration]
  ret = stack_trace_save(stack_buf, STACK_BUF_SIZE, 0);
        ^~~~~~~~~~~~~~~~
        stacktrace_driver
cc1: all warnings being treated as errors
scripts/Makefile.build:250: recipe for target 'lib/test_kprobes.o' failed
make[2]: *** [lib/test_kprobes.o] Error 1

To fix this error, Select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE is enabled.

Link: https://lore.kernel.org/all/[email protected]/

Fixes: 1f6d3a8 ("kprobes: Add a test case for stacktrace from kretprobe handler")
Cc: [email protected]
Signed-off-by: Li Hua <[email protected]>
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>

Author: LiHua-ProbeParker

lib/Kconfig.debug

@@ -2107,6 +2107,7 @@ config KPROBES_SANITY_TEST
 	depends on DEBUG_KERNEL
 	depends on KPROBES
 	depends on KUNIT
+	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
 	default KUNIT_ALL_TESTS
 	help
 	  This option provides for testing basic kprobes functionality on