The Great Tool Renaming, Part 2 (and hopefully last)

Hear ye, hear ye!

As I wrote previously, some tools, they've been a-changin':

Namely, `as' has gone away in favor of `llvm-as', similarly for `dis',
but NOW... `link' has become `llvm-link' because Redhat 8 (and probably
higher) ships with /bin/link (which seems like an `ln' clone) and we do
not want to conflict with it.

The appropriate changes have been made: tools/link no longer exists, the
Makefile(s) build llvm-link, etc.

Furthermore, I have removed tools/as and tools/dis as promised in the
previous email, so you can stop relying on them being called those
names. You can also start enjoying the fact that your LLVM executables
do not conflict with the system executables, so you can have your LLVM
tools/{Debug,Release} in the path at all times!!

Now that you're all elated, I'll let you get back to LLVM hacking.