ssl: Fix fd leak on write error

Reported by Coverity as CID #1167591
ssl: avoid null pointer dereference

name is checked not to be null earlier, if it is here just error
out.

Reported by Coverity as CID #1167590
spooler: fix use after free

Reported by Coverity as CID #1153073
spooler: filename cannot be null

Since it is allocated by uwsgi_malloc.
Reported by Coverity as CID #1153071
plugins/logpipe: check setsid return code

Reported by Coverity as CID #1167589
Merge pull request #518 from xrmx/coverity0802

Some coverity fixes