Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/lib64/cmake/llvm/AddLLVMDefinitions.cmake b/linux-x64/clang/lib64/cmake/llvm/AddLLVMDefinitions.cmake
new file mode 100644
index 0000000..dab1623
--- /dev/null
+++ b/linux-x64/clang/lib64/cmake/llvm/AddLLVMDefinitions.cmake
@@ -0,0 +1,17 @@
+# There is no clear way of keeping track of compiler command-line
+# options chosen via `add_definitions', so we need our own method for
+# using it on tools/llvm-config/CMakeLists.txt.
+
+# Beware that there is no implementation of remove_llvm_definitions.
+
+macro(add_llvm_definitions)
+  # We don't want no semicolons on LLVM_DEFINITIONS:
+  foreach(arg ${ARGN})
+    if(DEFINED LLVM_DEFINITIONS)
+      set(LLVM_DEFINITIONS "${LLVM_DEFINITIONS} ${arg}")
+    else()
+      set(LLVM_DEFINITIONS ${arg})
+    endif()
+  endforeach(arg)
+  add_definitions( ${ARGN} )
+endmacro(add_llvm_definitions)