llvm-config: Update help text for removal of "backend" pseudo component.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146708 91177308-0d34-0410-b5e6-96231b3b80d8

tools/llvm-config/llvm-config.cpp

@@ -149,7 +149,6 @@ Options:\n\
   --build-mode      Print build mode of LLVM tree (e.g. Debug or Release).\n\
 Typical components:\n\
   all               All LLVM libraries (default).\n\
-  backend           Either a native backend or the C backend.\n\
   engine            Either a native JIT or a bitcode interpreter.\n";
   exit(1);
 }