Use braces in multi-statement DEBUG() code [NFC]

By adding braces into the DEBUG statement we can make clang-format format code
such as:

  DEBUG(stmt1(); stmt2())

as multi-line code:

  DEBUG({
    stmt1();
    stmt2();
  });

This makes control-flow in debug statements easier to read.

llvm-svn: 220441
diff --git a/polly/lib/Support/SCEVValidator.cpp b/polly/lib/Support/SCEVValidator.cpp
index 3a8895f..6c38782 100644
--- a/polly/lib/Support/SCEVValidator.cpp
+++ b/polly/lib/Support/SCEVValidator.cpp
@@ -471,12 +471,20 @@
     return false;
 
   SCEVValidator Validator(R, SE, BaseAddress);
-  DEBUG(dbgs() << "\n"; dbgs() << "Expr: " << *Expr << "\n";
-        dbgs() << "Region: " << R->getNameStr() << "\n"; dbgs() << " -> ");
+  DEBUG({
+    dbgs() << "\n";
+    dbgs() << "Expr: " << *Expr << "\n";
+    dbgs() << "Region: " << R->getNameStr() << "\n";
+    dbgs() << " -> ";
+  });
 
   ValidatorResult Result = Validator.visit(Expr);
 
-  DEBUG(if (Result.isValid()) dbgs() << "VALID\n"; dbgs() << "\n";);
+  DEBUG({
+    if (Result.isValid())
+      dbgs() << "VALID\n";
+    dbgs() << "\n";
+  });
 
   return Result.isValid();
 }