[clang] Update uses of 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

Explicitly avoided changing the strings in the clang-format tests.

Differential Revision: https://reviews.llvm.org/D44975

llvm-svn: 332350
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index d45bbb6..0e1fb98 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -6961,8 +6961,8 @@
   if (NumEltsToInit != NumElts && MaybeElementDependentArrayFiller(FillerExpr))
     NumEltsToInit = NumElts;
 
-  DEBUG(llvm::dbgs() << "The number of elements to initialize: " <<
-        NumEltsToInit << ".\n");
+  LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: "
+                          << NumEltsToInit << ".\n");
 
   Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts);