Rename DEBUG macro to LLVM_DEBUG.
    
The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.

In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.

Differential Revision: https://reviews.llvm.org/D43624

llvm-svn: 332240
diff --git a/llvm/lib/CodeGen/GlobalISel/Combiner.cpp b/llvm/lib/CodeGen/GlobalISel/Combiner.cpp
index dbc9dbc..0bc5b87 100644
--- a/llvm/lib/CodeGen/GlobalISel/Combiner.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Combiner.cpp
@@ -40,7 +40,7 @@
   MRI = &MF.getRegInfo();
   Builder.setMF(MF);
 
-  DEBUG(dbgs() << "Generic MI Combiner for: " << MF.getName() << '\n');
+  LLVM_DEBUG(dbgs() << "Generic MI Combiner for: " << MF.getName() << '\n');
 
   MachineOptimizationRemarkEmitter MORE(MF, /*MBFI=*/nullptr);
 
@@ -61,7 +61,7 @@
         ++MII;
         // Erase dead insts before even adding to the list.
         if (isTriviallyDead(*CurMI, *MRI)) {
-          DEBUG(dbgs() << *CurMI << "Is dead; erasing.\n");
+          LLVM_DEBUG(dbgs() << *CurMI << "Is dead; erasing.\n");
           CurMI->eraseFromParentAndMarkDBGValuesForRemoval();
           continue;
         }
@@ -71,7 +71,7 @@
     // Main Loop. Process the instructions here.
     while (!WorkList.empty()) {
       MachineInstr *CurrInst = WorkList.pop_back_val();
-      DEBUG(dbgs() << "Try combining " << *CurrInst << "\n";);
+      LLVM_DEBUG(dbgs() << "Try combining " << *CurrInst << "\n";);
       Changed |= CInfo.combine(*CurrInst, Builder);
     }
     MFChanged |= Changed;