When using `clang` with `-flto=thin -save-stats=obj` to compile a multi-file program, `clang` will save internal statistics during the link time code generation to `<obj_dir>/.stats` because `BaseName` is empty. When multiple binaries are placed in the same directory, conflicts will be caused by identical filenames for statistics. This patch uses the output filename as the base name instead of the input when `-save-stats=obj`.

When linking a multi-file program with `-save-stats=obj`, `clang` will save internal statistics during the link-time code generation to `<obj_dir>/xxx.stats` where `xxx` is the first filename of inputs. This behavior is strange. Additionally, naming conflicts will occur when multiple binaries placed in the same directory depend on the same input (e.g., https://github.com/martinus/map_benchmark). This patch uses the output filename as the base name instead of the first input when `-save-stats=obj`.

When uslinking `clang` with `-flto=thin a multi-file program with `-save-stats=obj` to compile a multi-file program, `clang` will save internal statistics during the link -time code generation to `<obj_dir>/xxx.stats` because `BaseName` is emptywhere `xxx` is the first filename of inputs. This behavior is strange. When multiple binaries are placed in the same directoryAdditionally, naming conflicts will be caused by identical filenames for statistics.occur when multiple binaries placed in the same directory depend on the same input (e.g., https://github.com/martinus/map_benchmark). This patch uses the output filename as the base name instead of the first input when `-save-stats=obj`.