Clarify how dbgs() operates.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92083 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/Debug.cpp

@@ -105,7 +105,7 @@ raw_ostream &llvm::dbgs() {
         // force a debug dump.
         sys::AddSignalHandler(&debug_user_sig_handler, 0);
       // Otherwise we've already set the debug stream buffer size to
-      // zero, disabling buffering.
+      // zero, disabling buffering so it will output directly to errs().
     }
   } thestrm;