[CMake] Add LLVM_TOOLS_INSTALL_DIR to LLVMConfig.cmake

This is the more-correct fix to out-of-tree building. AddLLVM.cmake relies on this variable being set, so we should make sure it is set in LLVMConfig.cmake.

llvm-svn: 272279
diff --git a/llvm/cmake/modules/LLVMConfig.cmake.in b/llvm/cmake/modules/LLVMConfig.cmake.in
index 2034e5e..2bd0812 100644
--- a/llvm/cmake/modules/LLVMConfig.cmake.in
+++ b/llvm/cmake/modules/LLVMConfig.cmake.in
@@ -55,6 +55,7 @@
 set(LLVM_CMAKE_DIR "@LLVM_CONFIG_CMAKE_DIR@")
 set(LLVM_BINARY_DIR "${LLVM_INSTALL_PREFIX}")
 set(LLVM_TOOLS_BINARY_DIR "@LLVM_CONFIG_TOOLS_BINARY_DIR@")
+set(LLVM_TOOLS_INSTALL_DIR "@LLVM_TOOLS_INSTALL_DIR@")
 
 if(NOT TARGET LLVMSupport)
   include("@LLVM_CONFIG_EXPORTS_FILE@")