HEADSUP: Removing GNU binutils versions of nm, readelf etc.

[Ed Maste]

We've been using the ELF Tool Chain version of tools such as nm,
readelf, size and strings by default for some time. The Binutils
versions can currently be installed instead by setting
WITHOUT_ELFTOOLCHAIN_TOOLS in src.conf(5).

I'm planning to remove the Binutils versions before too long. The
patch is in review at https://reviews.freebsd.org/D3238.

If anyone is currently using WITHOUT_ELFTOOLCHAIN_TOOLS in order to
install the Binutils tools instead, I'd appreciate knowing why.

-Ed