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/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index a3a485c..38dc7533 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -536,8 +536,8 @@
     if (&I == V)
       V = UndefValue::get(I.getType());
 
-    DEBUG(dbgs() << "IC: Replacing " << I << "\n"
-                 << "    with " << *V << '\n');
+    LLVM_DEBUG(dbgs() << "IC: Replacing " << I << "\n"
+                      << "    with " << *V << '\n');
 
     I.replaceAllUsesWith(V);
     return &I;
@@ -559,7 +559,7 @@
   /// value, we can't rely on DCE to delete the instruction. Instead, visit
   /// methods should return the value returned by this function.
   Instruction *eraseInstFromFunction(Instruction &I) {
-    DEBUG(dbgs() << "IC: ERASE " << I << '\n');
+    LLVM_DEBUG(dbgs() << "IC: ERASE " << I << '\n');
     assert(I.use_empty() && "Cannot erase instruction that is used!");
     salvageDebugInfo(I);