infrastructure.

This was essentially work toward PGO based on a design that had several
flaws, partially dating from a time when LLVM had a different
architecture, and with an effort to modernize it abandoned without being
completed. Since then, it has bitrotted for several years further. The
result is nearly unusable, and isn't helping any of the modern PGO
efforts. Instead, it is getting in the way, adding confusion about PGO
in LLVM and distracting everyone with maintenance on essentially dead
code. Removing it paves the way for modern efforts around PGO.

Among other effects, this removes the last of the runtime libraries from
LLVM. Those are being developed in the separate 'compiler-rt' project
now, with somewhat different licensing specifically more approriate for
runtimes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191835 91177308-0d34-0410-b5e6-96231b3b80d8

subdirectories to traverse into.
 - Originally I wanted to avoid this and just autoscan, but this has one key
   flaw in that new subdirectories can not automatically trigger a rerun of the
   llvm-build tool. This is particularly a pain when switching back and forth
   between trees where one has added a subdirectory, as the dependencies will
   tend to be wrong. This will also eliminates FIXME implicitly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146436 91177308-0d34-0410-b5e6-96231b3b80d8

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146409 91177308-0d34-0410-b5e6-96231b3b80d8

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143634 91177308-0d34-0410-b5e6-96231b3b80d8

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143634 91177308-0d34-0410-b5e6-96231b3b80d8