Implementing a new $(sys.uptime) variable (Mantis #1134)

The $(sys.uptime) variable contains the number of mintues the system
has been up and running. It uses various techniques depending on the OS
platform to find the system uptime:

* sysinfo() for Linux platforms
* kstat() for Solaris platforms
* pstat_getproc() for HP-UX
* sysctl() for BSD platforms

Any platform which doesn't have one of these methods available will default
to a stat(/proc/1) to get the create time of the init process, which falls
within a few seconds of the boot time of the system. (Even though Linux and
Solaris have /proc, this method is not used on those platforms even as a
fallback.)

If any of these approaches fail, the routine falls back to running the
"/usr/bin/uptime" or "/bin/uptime" command, and its output is parsed into
days, hours, and minutes with a PCRE regexp, and converted to a usable time
for the variable. Thanks to Ted Zlatanov for the suggestion: https://github.com/cfengine/core/pull/46#issuecomment-10066632

This popen() approach is unlikely to be used very frequently - probably only if
the /proc filesystem isn't mounted - but it's a decent backstop to give a
system the best possible chance to set $(sys.uptime) successfully.

Two other closely related variables are introduced: $(sys.systime) and
$(sys.sysday). The former is simply the result of the time() system call,
which is useful in manipulating timestamps in HP-UX TCB password databases,
for example, and the latter is that value divided by 86,400 - the number of
seconds in a day - expressed as an integer. This is, of course, useful in the
/etc/shadow file to indicate the password change date.

Three new documents are added in docs/reference/vars to describe the
$(sys.uptime), $(sys.systime), and $(sys.sysday) variables.
BSD <sys/param.h> include is required for <sys/sysctl.h> header checks

See also jail.h, sys/mount.h checks.
64-bit time_t snprintf; cf_popen needs pipes.h - for sys.uptime var

The cf_popen() and cf_pclose() calls now need to have pipes.h included,
because it was factored out in commit 5be64d09bc4c9c9659d53d2b5bf61286f768acbf.

The time_t type needs the proper printf format to support both 32- and 64-bit
platforms. On older platforms which don't have a C99-compliant snprintf, the
"pub/snprintf.c" replacement is used, so that a "%jd" format can be used even
on such platforms. Normally they would use the PRIdMAX definition from
inttypes.h. See commit f6ba42d5b2988be1f94ee4e55baa174fd7906362.
Added a check if we start with the keyword "bundle" or "body" + unit test
add process name and pid in syslog message sent by RemoteSysLog

RemoteSysLog is usefull when real syslog is not available. As explained in
rfc3164 (§5.3) we should provide process information as process name and pid.
This make filtering message much more easy.
Don't truncate IPV6 addresses in cf-key -s output
Don't truncate IPv6 addresses in cf-key -s output (part2)
Add support for Debian's GNU/kfreebsd

See http://sources.debian.net/src/cfengine3/3.2.4-2%2Bnmu1/debian/patches/626647-kfreebsd-support.patch for reference.
Merge remote branch 'upstream/master'
Merge commit 'mvpel/sys_uptime'

Conflicts:
	libpromises/sysinfo.c
Add tests for $(sys.uptime/systime/sysday).
add check for support of vnsprintf/C99 compiler to fix runtime bug
Merge pull request #803 from McAtte/master

Fix solaris 9 unit test failure of policy_test
Fix redmine #2936
Change testall script to expect being in OBJDIR/tests/acceptance

A clear error message is printed if this is not the case. This way we
avoid looking for cf-* executables in erroneous directories, which
happened when building out of source directory.
Add acceptance tests for redmine #2936.
reindent libraries/*.cf and lib/*/*.cf
reindent the rest of masterfiles/**/*.cf
fix up XML indentation for guest environments
Merge pull request #809 from kacfengine/sys_uptime

Sys uptime