Merge pull request swiftlang#35408 from eeckstein/remove-deb-api

SILOptimizer: remove the unused DeadEndBlocks::empty() API

Author: eeckstein

include/swift/SIL/BasicBlockUtils.h

@@ -81,15 +81,6 @@ class DeadEndBlocks {
     return ReachableBlocks.count(block) == 0;
   }
 
-  bool empty() {
-    if (!isComputed) {
-      // Lazily compute the dataflow.
-      compute();
-      isComputed = true;
-    }
-    return ReachableBlocks.empty();
-  }
-
   const SILFunction *getFunction() const { return F; }
 };