Add a PACKGECONFIG to control the building of the beecrypt C++
bindings. The only user of beecrypt in OE-Core is rpm and this doesn't
need the C++ bindings so default the option to be off. This means
we can lose the icu dependency by default which is a significant
performance win.
(From OE-Core rev: e6885069e2af833ebacfd33a04147b095af92d20)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>