tests: use sprintrc in tests/ptrace.c
tests: use sprintrc in tests/ptrace.c

* tests/ptrace.c (errstr): New static variable.
(do_ptrace): Initialize it using sprintrc.
(test_peeksiginfo, main): Use errstr.

cuviper/strace,cuviper/strace,cuviper/strace,cuviper/strace,cuviper/strace