[PM] Make the AnalysisManager parameter to run methods a reference.

This was originally a pointer to support pass managers which didn't use
AnalysisManagers. However, that doesn't realistically come up much and
the complexity of supporting it doesn't really make sense.

In fact, *many* parts of the pass manager were just assuming the pointer
was never null already. This at least makes it much more explicit and
clear.

llvm-svn: 263219
diff --git a/llvm/lib/Analysis/LazyCallGraph.cpp b/llvm/lib/Analysis/LazyCallGraph.cpp
index 5de9078..36425c9 100644
--- a/llvm/lib/Analysis/LazyCallGraph.cpp
+++ b/llvm/lib/Analysis/LazyCallGraph.cpp
@@ -1531,8 +1531,8 @@
 }
 
 PreservedAnalyses LazyCallGraphPrinterPass::run(Module &M,
-                                                ModuleAnalysisManager *AM) {
-  LazyCallGraph &G = AM->getResult<LazyCallGraphAnalysis>(M);
+                                                ModuleAnalysisManager &AM) {
+  LazyCallGraph &G = AM.getResult<LazyCallGraphAnalysis>(M);
 
   OS << "Printing the call graph for module: " << M.getModuleIdentifier()
      << "\n\n";