Replace "fallthrough" comments with LLVM_FALLTHROUGH

This is a mechanical change of comments in switches like fallthrough,
fall-through, or fall-thru to use the LLVM_FALLTHROUGH macro instead.

llvm-svn: 278902
diff --git a/llvm/lib/CodeGen/ScoreboardHazardRecognizer.cpp b/llvm/lib/CodeGen/ScoreboardHazardRecognizer.cpp
index 69c4870..83bc1ba 100644
--- a/llvm/lib/CodeGen/ScoreboardHazardRecognizer.cpp
+++ b/llvm/lib/CodeGen/ScoreboardHazardRecognizer.cpp
@@ -145,7 +145,7 @@
       case InstrStage::Required:
         // Required FUs conflict with both reserved and required ones
         freeUnits &= ~ReservedScoreboard[StageCycle];
-        // FALLTHROUGH
+        LLVM_FALLTHROUGH;
       case InstrStage::Reserved:
         // Reserved FUs can conflict only with required ones.
         freeUnits &= ~RequiredScoreboard[StageCycle];
@@ -197,7 +197,7 @@
       case InstrStage::Required:
         // Required FUs conflict with both reserved and required ones
         freeUnits &= ~ReservedScoreboard[cycle + i];
-        // FALLTHROUGH
+        LLVM_FALLTHROUGH;
       case InstrStage::Reserved:
         // Reserved FUs can conflict only with required ones.
         freeUnits &= ~RequiredScoreboard[cycle + i];