Communicate PIPE_BUF default value to test suite

On platforms that don't define PIPE_BUF (such as GNU Hurd), we assume a
value of 512 in src/server/fifo.c (as POSIX guarantees PIPE_BUF >= 512).
We now communicate this default value to Autotest in order to fix the
corresponding test case on such platforms.
Fix test cases for GNU Hurd

GNU Hurd doesn't like the the trick we're using in tests/test_nsca.c to
avoid having to wait until the server notices that we opened the command
file for reading.  This means that each check might block for a few
seconds on Hurd, but that's still preferable to failing test cases.
m4/aio.m4: Check whether AIO signals are delivered

At least on Debian GNU/kFreeBSD 7.0 RC1, the POSIX AIO implementation
fails to deliver completion notification signals (but seems to work
otherwise).  The ./configure script now detects this case and then
disables POSIX AIO usage.
Use fstat(2) to check if command file is a FIFO

Use fstat(2) rather than stat(2) to check whether the command file is a
named pipe.  This fixes a race condition in the case where the command
file is recreated after the NSCA-ng server has open(2)ed it.
Apply another test suite fix for GNU Hurd

On GNU Hurd, opening the FIFO sometimes fails with EINTR (even though no
signal has been delivered).
Minor test suite cleanups

Move all capturing of "input" files into tests/local.at:NSCA_CHECK().
Also, don't capture "expout" files.  If the actual output doesn't match
the expected output, the diff(1) is included anyway.
Don't call OPENSSL_config(3)

The OPENSSL_config(3) man page claims that this function "ignores all
errors", but that's not true: at least OpenSSL 1.0.1e exit(3)s on
certain error conditions in the OPENSSL_config(3) function (e.g., if the
check whether the configuration file exists fails due to missing
permissions).  We therefore no longer call this function.
Update embedded libev code to version 4.15

Update our copy of libev from version 4.11 to version 4.15.  The new
release provides a number of bug fixes and minor enhancements.
Explicitly ignore ev_run()'s return value

The ev_run() function returns a boolean value as of libev 4.15.
m4/aio.m4: Prefix variable name with "nsca"
Makefile.am: Cosmetic change
TODO: Add OpenSSL-related tasks

Also list wish list items that require OpenSSL to be patched (so that we
have a place to save any relevant URLs).
Convert ChangeLog from UTF-8 to US-ASCII

Transliterate any non-ASCII characters when creating the ChangeLog file
from the Git history.
Close open file descriptors on server startup

Let nsca-ng(8) close any inherited file descriptors (except for stdin,
stdout, and stderr) on startup.
etc/nsca-ng.cfg: Cosmetic change

We usually use the file extension ".cfg" for configuration files.
Support include(<directory>) in nsca-ng.cfg(5)

Let nsca-ng.cfg(5)'s "include" directive accept directory path names.
If a directory is specified, include all "*.cfg" and "*.conf" files in
this directory and all subdirectories.
TODO: Add another wish list item

The server should allow the user to specify one or more permitted
subnets.  Connections from clients outside these subnets should be
rejected.
Let the server accept "-c <directory>"

If a directory is specified via nsca-ng(8)'s "-c" flag, read the
configuration from all "*.cfg" and "*.conf" files in the specified
directory and all subdirectories.
Don't confuse libConfuse when including trees

When including configuration files in a directory tree recursively, call

	cfg_parse_buf(cfg, "include(<file>)")

for every included file instead of using the cfg_include() function
directly.  This is necessary to keep libConfuse's internal state
consistent.  The library would otherwise reject to include more than
MAX_INCLUDE_DEPTH (currently 10) files per directory tree, among other
issues.
Fix a (harmless) memory leak

When including files or directories, free(3) the memory allocated by
libConfuse's cfg_tilde_expand() function.