llvm2: don't install llvm-config to bindir

* there is llvm-config in binconfig/LLVM_RELEASE
* this one was creating conflict between different llvm*-dev versions
  installed on target:
  ./llvm2.9/2.9-r3/packages-split/llvm2.9-dev/usr/bin/llvm2.9/llvm-config
  ./llvm2.9/2.9-r3/packages-split/llvm2.9-dev/usr/bin/llvm-config
  ./llvm2.8/2.8-r3/packages-split/llvm2.8-dev/usr/bin/llvm2.8/llvm-config
  ./llvm2.8/2.8-r3/packages-split/llvm2.8-dev/usr/bin/llvm-config

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>