(https://github.com/SNSystems/llvm-prepo/issues/10) Add a short comme…

…nt to explain the previous change.

lib/Driver/ToolChains/Clang.cpp

@@ -3404,6 +3404,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // Enable -mconstructor-aliases except on darwin, where we have to work around
   // a linker bug (see <rdar://problem/7651567>), and CUDA device code, where
   // aliases aren't supported.
+  // The program repo's digest-generation and pruning passes don't currently
+  // support aliases, so disable them here.
   if (!RawTriple.isOSDarwin() && !RawTriple.isNVPTX() &&
       !RawTriple.isOSBinFormatRepo())
     CmdArgs.push_back("-mconstructor-aliases");