[PM] Port StripDeadPrototypes to the new pass manager

This is a really straightforward port. Also adds a test for the pass,
since it only seemed to be tested tangentially before.

llvm-svn: 251726
diff --git a/llvm/lib/Transforms/IPO/IPO.cpp b/llvm/lib/Transforms/IPO/IPO.cpp
index 7ecc377..97e4584 100644
--- a/llvm/lib/Transforms/IPO/IPO.cpp
+++ b/llvm/lib/Transforms/IPO/IPO.cpp
@@ -40,7 +40,7 @@
   initializeMergeFunctionsPass(Registry);
   initializePartialInlinerPass(Registry);
   initializePruneEHPass(Registry);
-  initializeStripDeadPrototypesPassPass(Registry);
+  initializeStripDeadPrototypesLegacyPassPass(Registry);
   initializeStripSymbolsPass(Registry);
   initializeStripDebugDeclarePass(Registry);
   initializeStripDeadDebugInfoPass(Registry);