Does not build with latest cmake

[jbush001]

jbush001/NyuziProcessor#204

[jbush001]

CMake Error at /usr/share/cmake/Modules/ExternalProject.cmake:2471:EVAL:2 (add_custom_command):
Error evaluating generator expression:

$<TARGET_FILE:llvm-ranlib>

Target "llvm-ranlib" is not an executable or library.
Call Stack (most recent call first):
/usr/share/cmake/Modules/ExternalProject.cmake:2471 (cmake_language)
cmake/modules/LLVMExternalProjectUtils.cmake:239 (ExternalProject_Add_Step)
runtimes/CMakeLists.txt:216 (llvm_ExternalProject_Add)
runtimes/CMakeLists.txt:275 (builtin_default_target)

CMake Error at /usr/share/cmake/Modules/ExternalProject.cmake:2471:EVAL:2 (add_custom_command):
Error evaluating generator expression:

$<TARGET_FILE:llvm-strip>

Target "llvm-strip" is not an executable or library.
Call Stack (most recent call first):
/usr/share/cmake/Modules/ExternalProject.cmake:2471 (cmake_language)
cmake/modules/LLVMExternalProjectUtils.cmake:239 (ExternalProject_Add_Step)
runtimes/CMakeLists.txt:216 (llvm_ExternalProject_Add)
runtimes/CMakeLists.txt:275 (builtin_default_target)

CMake Error at /usr/share/cmake/Modules/ExternalProject.cmake:2471:EVAL:2 (add_custom_command):
Error evaluating generator expression:

$<TARGET_FILE:llvm-ranlib>

Target "llvm-ranlib" is not an executable or library.
Call Stack (most recent call first):
/usr/share/cmake/Modules/ExternalProject.cmake:2471 (cmake_language)
cmake/modules/LLVMExternalProjectUtils.cmake:239 (ExternalProject_Add_Step)
runtimes/CMakeLists.txt:216 (llvm_ExternalProject_Add)
runtimes/CMakeLists.txt:275 (builtin_default_target)

CMake Error at /usr/share/cmake/Modules/ExternalProject.cmake:2471:EVAL:2 (add_custom_command):
Error evaluating generator expression:

$<TARGET_FILE:llvm-strip>

Target "llvm-strip" is not an executable or library.
Call Stack (most recent call first):
/usr/share/cmake/Modules/ExternalProject.cmake:2471 (cmake_language)
cmake/modules/LLVMExternalProjectUtils.cmake:239 (ExternalProject_Add_Step)
runtimes/CMakeLists.txt:216 (llvm_ExternalProject_Add)
runtimes/CMakeLists.txt:275 (builtin_default_target)