Commits
Michael Gottesman committed 7505b6b8ddc
[lto] Use -DLLVM_ENABLE_LTO to enable llvm lto instead of -DCMAKE_{C,CXX}_FLAGS
This not only is the more canonical way to enable lto in LLVM but in addition
without this change, the swift compiler unittests will not build with LTO
resulting in funky LTO errors like rdar://25968091.
rdar://24717107