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/Target/AMDGPU/AMDGPUInline.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInline.cpp
index ca77795..35dd9eb 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInline.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInline.cpp
@@ -161,8 +161,8 @@
       return false;
     }
     if (isa<ReturnInst>(*std::next(I->getIterator()))) {
-      DEBUG(dbgs() << "    Wrapper only call detected: "
-                   << Callee->getName() << '\n');
+      LLVM_DEBUG(dbgs() << "    Wrapper only call detected: "
+                        << Callee->getName() << '\n');
       return true;
     }
   }