bcmp, bcopy, bzero are removed from XPG7

[Garrett D'Amore]

The strict XPG7 spec removed the legacy BSD string handling.

[Garrett D'Amore]

Also, index, and rindex.

Note that the way I'm changing this, the functions will not be exposed in "strict" conformance except under XPG4.2, SUSv2, and SUSv3. That's the only place they should be exposed when compiling wit strict conformance.

(As side node; it's unclear to me whether the implementation is permitted to supply additional headers in strictly conformant C mode. I've taken the approach that in such cases we should still not expose symbols into the application. Folks using strict conformance compilation want to be sure that their namespace is "clean".)

[Garrett D'Amore]

fixes #16 bcmp, bcopy, bzero are removed from XPG7

→ <<cset c500f6a2d018>>