Add more SUBDIR_PARALLEL.

This is "make tinderbox" clean.

To enable them, set WITH_GCC and WITH_GNUCXX in src.conf.
Make clang default to using libc++ on FreeBSD 10.
Bumped __FreeBSD_version for the change.

GCC is still enabled on PC98, because the PC98 bootloader requires GCC to build
(or, at least, hard-codes the use of gcc into its build).

Thanks to everyone who helped make the ports tree ready for this (and bapt
for coordinating them all).  Also to imp for reviewing this and working on the
forward-porting of the changes in our gcc so that we're getting to a much
better place with regard to external toolchains.

Sorry to all of the people who helped who I forgot to mention by name.

Reviewed by:	bapt, imp, dim, ...

extremely outdated, and not used by anything in the base system.

Silence from:	current@

dialog is distributed from GPLv2 to LGPLv2 and introduces a number of new
features and a new and better libdialog API. The existing libdialog will
be kept temporarily as libodialog for compatibility purposes until sade,
sysinstall and tzsetup have been either updated or replaced.

__FreeBSD_version is now 900030.

Discussed on:	-current
Approved by:	core
Obtained from:	http://invisible-island.net/dialog

- It is opt-out for now so as to give it maximum testing, but it may be
  turned opt-in for stable branches depending on the consensus.  You
  can turn it off with WITHOUT_SSP.
- WITHOUT_SSP was previously used to disable the build of GNU libssp.
  It is harmless to steal the knob as SSP symbols have been provided
  by libc for a long time, GNU libssp should not have been much used.
- SSP is disabled in a few corners such as system bootstrap programs
  (sys/boot), process bootstrap code (rtld, csu) and SSP symbols themselves.
- It should be safe to use -fstack-protector-all to build world, however
  libc will be automatically downgraded to -fstack-protector because it
  breaks rtld otherwise.
- This option is unavailable on ia64.

Enable GCC stack protection (aka Propolice) for kernel:
- It is opt-out for now so as to give it maximum testing.
- Do not compile your kernel with -fstack-protector-all, it won't work.

Submitted by:	Jeremie Le Hen <jeremie@le-hen.org>

Also:
        Switch FreeBSD to use libgcc_s.so.1.

        Use dl_iterate_phdr to locate shared objects' exception frame
        info instead of depending on older register_frame_info machinery.
        This allows us to avoid depending on libgcc_s.so.1 in binaries
        that do not use exception handling directly. As an additional
        benefit it breaks circular libc <=> libgcc_s.so.1 dependency too.

        Build newly added libgomp.so.1 library, the runtime support
        bits for OpenMP.

        Build LGPLed libssp library. Our libc provides our own
        BSD-licensed SSP callbacks implementation, so this library
        is only built to benefit applications that have hadcoded
        knowledge of libssp.so and libssp_nonshared.a. When linked
        in from command line, these libraries override libc
        implementation.

http://lists.freebsd.org/pipermail/freebsd-current/2006-March/061725.html

The src.conf(5) manpage is to follow in a few days.

Brought to you by:	imp, jhb, kris, phk, ru (all bugs are mine)