MFC r319056,r319058,r319059,r319060,r319061,r319078:

r319056:

tests/sys/file/ftruncate_test: use an exit code of 1 instead
of -1 with err*(3).

An exit code of -1 is implementation defined -- it's best to stick
with something well-defined (1).

r319058:

Create a deterministic file in the kyua sandbox, instead of a
temporary file outside the kyua sandbox

This helps ensure that the file is removed at test exit, and as
a side effect, cures a warning about umasks with Coverity.

r319059:

Use an exit code of 1 instead of -1 for reasons noted in r319056

r319060:

Use main(void) instead of main(argc unused, argv unused)

r319061:

Don't leak accept_fd on thread completion

CID: 1296068

r319078:

Tweak r319058 slightly

• Specify an explicit mode when using O_CREAT per open(2).
• Fix the error message (add missing enclosing parentheses).

MFC with: r319058