Log Message:
textproc/enchant2: Clean up USE_LANGUAGES

There was FORCE_CXX_STD=c++11, blamed on hunspell, but enchant2 now
outright requires c++11 itself, probes for options, and sets --std.
The only thing wrong is not noting that requirement in README.
Therefore, simply USE_CXX_FEATURES as c++11 and drop FORCE_CXX_STD.

Move USE_LANGUAGES to its own block before tools, following
convention; sorting USE_CXX_FEATURES and USE_LANGUAGES backwards makes
it hard to follow.

This shouldn't change the binary package, unless perhaps a compiler is
defaulting to a newer std and produces different binary in c++11 vs
c++newer mode, in which case ride yesterday's update.