llvm-project

f7562246 - [llvm-lto2] Added llvm-lto2 -unified-lto descriptions (revised) (#155462)

[llvm-lto2] Added llvm-lto2 -unified-lto descriptions (revised) (#155462) This is a revised PR of #148309 (closed due to some git issues). The changes do the following: - Adds description for the modes of `-unified-lto=mode` option - Changes parsing of `unified-lto` descriptions from string to cEnumValN for continuity of description formatting - Adds testing of error output in `unified-lto-check.ll`