When falloc() was broken into separate falloc_noinstall() and finstall(), a bug was introduced in kern_openat() such that the error from the vnode open operation was overwritten before it was passed as an argument to dupfdopen().  This broke operations on /dev/{stdin,stdout,stderr}.  Fix by preserving the original error number across finstall() so that it is still available.
When falloc() was broken into separate falloc_noinstall() and finstall(),
a bug was introduced in kern_openat() such that the error from the vnode
open operation was overwritten before it was passed as an argument to
dupfdopen().  This broke operations on /dev/{stdin,stdout,stderr}.  Fix
by preserving the original error number across finstall() so that it is
still available.

Approved by:	re (kib)
Reported by:	cognet

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase