Don't use now-defunct cmake variable in lit test config

[ROCm/hip commit: 59071b895e]

projects/hip/tests/hipify-clang/lit.site.cfg.in

@@ -1,7 +1,7 @@
 import sys
 
 config.llvm_tools_dir = "@LLVM_TOOLS_BINARY_DIR@"
-config.obj_root = "@BINARY_DIR@"
+config.obj_root = "@CMAKE_CURRENT_BINARY_DIR@"
 config.cuda_root = "@CUDA_TOOLKIT_ROOT_DIR@"
 
 # Support substitution of the tools and libs dirs with user parameters. This is