[analyzer] Rename generateNode -> addTransition in CheckerContext

Also document addTransition methods.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143059 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp b/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp
index 202522b..845ae4f 100644
--- a/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp
@@ -50,7 +50,7 @@
   if (isa<VarRegion>(LR) || isa<CodeTextRegion>(LR) || 
       isa<CompoundLiteralRegion>(LR)) {
 
-    if (ExplodedNode *N = C.generateNode()) {
+    if (ExplodedNode *N = C.addTransition()) {
       if (!BT)
         BT.reset(new BuiltinBug("Dangerous pointer arithmetic",
                             "Pointer arithmetic done on non-array variables "