[lld] 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

Differential Revision: https://reviews.llvm.org/D44977

llvm-svn: 332351
diff --git a/lld/wasm/MarkLive.cpp b/lld/wasm/MarkLive.cpp
index 95d9782..7c4670d 100644
--- a/lld/wasm/MarkLive.cpp
+++ b/lld/wasm/MarkLive.cpp
@@ -37,7 +37,7 @@
   if (!Config->GcSections)
     return;
 
-  DEBUG(dbgs() << "markLive\n");
+  LLVM_DEBUG(dbgs() << "markLive\n");
   SmallVector<InputChunk *, 256> Q;
 
   auto Enqueue = [&](Symbol *Sym) {