MFC r239680:

MFC r239680:

  Add libcxxrt's objects (prefixing them with cxxrt_ to avoid collisions)
  to libc++.a and libc++_p.a, to make static linking of C++ executables
  with libc++ easier.  This is similar to the approach used in libstdc++.

MFC r239686:

  When using -stdlib=libc++, add the correct dependency to .depend in
  bsd.prog.mk.

  Submitted by:	Yamaya Takashi <yamayan@kbh.biglobe.ne.jp>

MFC r239695:

  For building libstdc++ and libsupc++, filter out any -stdlib=libc++
  option from CXXFLAGS, otherwise these libraries will not build.
  Similarly, filter out any -std=xxx options that aren't supported.

  Submitted by:	Yamaya Takashi <yamayan@kbh.biglobe.ne.jp>

git-svn-id: svn://svn.freebsd.org/base/stable/9@240236 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f