x/sys/unix: PR_SET_PTRACER_ANY missing for linux_arm conditional compilation

[nvb]

The PR_SET_PTRACER_ANY system error number is missing from the // +build arm,linux version of zerror_${GOOS}_${GOARCH}.go, but is available for all other linux builds. This results in the compilation of code like https://github.com/backtrace-labs/go-bcd/blob/master/bcd_sys_linux.go to fail on 32-bit arm architectures.

I haven't been able to find any reason why this flag would be missing, so I'm curious if the correct approach would be to add something like:

#ifndef PR_SET_PTRACER_ANY
#define PR_SET_PTRACER_ANY  -0x1
#endif

directly after the other default error codes in the mkerrors.sh generation script.

[tklauser]

This should be fixed by golang/sys@ea9bcad.

[ianlancetaylor]

Yes, fixed by https://golang.org/cl/37943. Thanks for pointing that out.