[dsymutil] Rename llvm-dsymutil -> dsymutil

Now that almost all functionality of Apple's dsymutil has been
upstreamed, the open source variant can be used as a drop in
replacement. Hence we feel it's no longer necessary to have the llvm
prefix.

Differential revision: https://reviews.llvm.org/D44527

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@327790 91177308-0d34-0410-b5e6-96231b3b80d8
66 files changed