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/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 1300a92..4a01c11 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3780,8 +3780,8 @@
     // Remove the convergent attr on calls when the callee is not convergent.
     if (CS.isConvergent() && !CalleeF->isConvergent() &&
         !CalleeF->isIntrinsic()) {
-      DEBUG(dbgs() << "Removing convergent attr from instr "
-                   << CS.getInstruction() << "\n");
+      LLVM_DEBUG(dbgs() << "Removing convergent attr from instr "
+                        << CS.getInstruction() << "\n");
       CS.setNotConvergent();
       return CS.getInstruction();
     }