libgo patch committed: Restore line lost in libgo merge

[Ian Lance Taylor]

PR 64573 points out that a line was somehow lost when merging from the
master library to libgo.  This patch restores the line.  Bootstrapped
and ran Go testsuite on x86_64-unknown-linux-gnu.  Committed to
mainline.

Ian

diff -r b7495eb183c7 libgo/go/syscall/exec_unix.go
--- a/libgo/go/syscall/exec_unix.go     Fri Jan 23 15:21:30 2015 -0800
+++ b/libgo/go/syscall/exec_unix.go     Fri Jan 23 15:42:16 2015 -0800
@@ -226,6 +226,7 @@
        // Kick off child.
        pid, err1 = forkAndExecInChild(argv0p, argvp, envvp, chroot, dir, attr, 
sys, p[1])
        if err1 != 0 {
+               err = Errno(err1)
                goto error
        }
        ForkLock.Unlock()