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/utils/TableGen/AsmMatcherEmitter.cpp b/llvm/utils/TableGen/AsmMatcherEmitter.cpp
index def1447..9ff2410 100644
--- a/llvm/utils/TableGen/AsmMatcherEmitter.cpp
+++ b/llvm/utils/TableGen/AsmMatcherEmitter.cpp
@@ -1091,7 +1091,7 @@
     // Verify that any operand is only mentioned once.
     // We reject aliases and ignore instructions for now.
     if (!IsAlias && Tok[0] == '$' && !OperandNames.insert(Tok).second) {
-      DEBUG({
+      LLVM_DEBUG({
         errs() << "warning: '" << TheDef->getName() << "': "
                << "ignoring instruction with tied operand '"
                << Tok << "'\n";
@@ -1477,7 +1477,7 @@
                            SubtargetFeaturePairs.end());
 #ifndef NDEBUG
   for (const auto &Pair : SubtargetFeatures)
-    DEBUG(Pair.second.dump());
+    LLVM_DEBUG(Pair.second.dump());
 #endif // NDEBUG
   assert(SubtargetFeatures.size() <= 64 && "Too many subtarget features!");