re PR go/81324 (libgo does not build with glibc 2.18)
PR go/81324
sysinfo.c: ignore ptrace_peeksiginfo_args from <linux/ptrace.h>
With some versions of glibc and GNU/Linux ptrace_pseeksiginfo_args is
defined in both <sys/ptrace.h> and <linux/ptrace.h>. We don't actually
care about the struct, so use a #define to avoid a redefinition error.