Fix an uninitialized variable as well as an stdarg cleanup. (CID: 1194318 and 1194332)

[araujo]

Summary

CID 1194318: We call the macro EFPRINTF without initialize the variable err.
CID 1194332: stdarg(3) says that each invocation of va_start() must be paired with a corresponding invocation of va_end() in the same function. In this case if an error occur with vfprintf() we forget to call va_end(ap).

Test Plan

Tested with FreeeBSD HEAD as a vm guest.
Tested with Fedora as a vm guest.

[araujo]

oooops, I opened a revision with the wrong file 🗡