merge from another 1.3.1
Fix for http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=680146
Don't mark the following AVPs as mandatory:
  - Firmware Revision
  - Vendor name
  - Rx Connect speed
  - Physical channel ID

(from https://github.com/richvdh/xl2tpd/commit/af60a268dd590456c0e0a16da745e1ce748e13d7)
Respect CFLAGS for xl2tpd-control.
Merge remote-tracking branch 'tphelps/master' into testing
Merge remote-tracking branch 'floppym/master' into testing
Fix kernel support for 2.6.23+

Kernel support was broken since 2.6.23+
This patch fixes it.
Many thanks to wl500g.googlecode.com project for idea and help.
Remove if_pppol2tp.h header

if_pppol2tp.h header is not compatible with newer kernels.
We may drop it to use /usr/include/linux one.
Enable kernel-mode by default
Actually force userspace when using SAref.

Currently only warning is printed, but value don't switch actually.
Wrap connect_pppol2tp() with ifdef

Eliminate excess function call if USE_KERNEL is disabled.
Merge remote-tracking branch 'sigwall/kernel' into testing
Cope with comment lines that extend beyond 120 characters.  Otherwise xl2tpd
will try to interpret the 120th character of the line as the start of the
next line, which will usually end in a cryptic error message.  See also
Fedora BZ#806963.
Increase the size of the buffer used to read config file lines.

The config file format treats any character after a semicolon as a comment,
so that people can comment config after the line.  The current line limit
of 120 characters is easy enough to overflow with this sort of (sane)
documentation style; let's increase it to 1024 bytes.  Patch from Fedora's
bz#806963.
Don't call grantpt().

Use of grantpt() is fraught: we run with a SIGCHLD handler, which
can lead to undefined results on systems that exec a setuid child
process to fiddle the ownership/permissions of the slave pty when a
child pppd process dies at just the right moment.  In addition, it
reportedly interacts badly with SELinux.

It turns out that there's no need to call grantpt() anyway.  Child pppd
processes run as root and so should be able to access the slave ptys with
their original ownership and permissions.  On FreeBSD/Mac OS X, grantpt()
doesn't actually do anything interesting and has been presumably been
working fine.  Fedora has been shipping with a patch to disable the call
to grantpt, and OpenBSD is completely unaffected, so this looks pretty
safe.
Quash more valgrind warnings.

Valgrind warns that not all fields in the sockaddr_pppol2tp struct are
getting initialized.  Use memset to ensure that everything not explicitly
set will be cleared to zero, which should ensure that this continues to work
even if Linux adds new fields to the struct.
Merge pull request #7 from tphelps/master

Minor tweaks
Merge pull request #8 from floppym/master

Respect CFLAGS for xl2tpd-control
Merge pull request #9 from sigwall/kernel

Fix kernel support for 2.6.23+
Merge pull request #10 from tphelps/fedora-pty

Fedora pty
Merge pull request #11 from tphelps/bz806963

Bz806963