lang/pypy: update to 2.6.1

Changes:

• Add external cffi ports (a la python):
  • databases/pypy-gdbm
  • databases/pypy-sqlite3
  • x11-toolkits/pypy-tkinter
• Add bsd.pypy.mk for consistency between pypy ports.
• Add bsd.pypy.cffi.mk for consistency with external cffi ports.
• Switch back to using $PREFIX/pypy-X.Y (the '-' separator is required to differentiate between lang/pypy and lang/pypy3)
• Remove all patches (upstreamed, see announcement below)

ChangeLog:

• Bug Fixes
  • Revive non-SSE2 support
  • Fixes for detaching _io.Buffer*
  • Clear up contention in the garbage collector between trace-me-later and pinning
  • Issues reported with our previous release were resolved after reports from users on our issue tracker at https://bitbucket.org/pypy/pypy/issues or on IRC at #pypy.
• New features:
  • cffi was updated to version 1.3
  • The python stdlib was updated to 2.7.10 from 2.7.9
  • vmprof now supports multiple threads
  • The translation process builds cffi import libraries for some stdlib packages, which should prevent confusion when package.py is not used
  • better support for gdb debugging
  • FreeBSD should be able to translate PyPy "out of the box" with no patches
• Numpy:
  • Better support for record dtypes, including the align keyword
  • Implement casting and create output arrays accordingly (still missing some corner cases)
  • Support creation of unicode ndarrays
  • Better support ndarray.flags
  • Support axis argument in more functions
  • Refactor array indexing to support ellipses
  • Allow the docstrings of built-in numpy objects to be set at run-time
  • Support the buffered nditer creation keyword
• Performance improvements:
  • Delay recursive calls to make them non-recursive
  • Skip loop unrolling if it compiles too much code
  • Tweak the heapcache
  • Add a list strategy for lists that store both floats and 32-bit integers. The latter are encoded as nonstandard NaNs. Benchmarks show that the speed of such lists is now very close to the speed of purely-int or purely-float lists.
  • Simplify implementation of ffi.gc() to avoid most weakrefs
  • Massively improve the performance of map() with more than one sequence argument

Differential Revision: https://reviews.freebsd.org/D3285