Configuring the variable in CMake isn't enought, because the build mode
can't be resolved until execution time, which requires the build mode to
be substituted by lit.
config.dsymutil = config.dsymutil % lit_config.params
config.filecheck = config.filecheck % lit_config.params
config.yaml2obj = config.yaml2obj % lit_config.params
+ config.lldb_framework_dir = config.lldb_framework_dir % lit_config.params
config.dotest_args_str = config.dotest_args_str % lit_config.params
except KeyError as e:
key, = e.args