[analyzer] Refactor checkers to use helper function for getting callee Decl and name.

We are getting name of the called function or it's declaration in a few checkers. Refactor them to use the helper function in the CheckerContext. 

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145576 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp b/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp
index bc6e8f3..1f62729 100644
--- a/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp
+++ b/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp
@@ -249,11 +249,8 @@
 
 void CFNumberCreateChecker::checkPreStmt(const CallExpr *CE,
                                          CheckerContext &C) const {
-  const Expr *Callee = CE->getCallee();
   const ProgramState *state = C.getState();
-  SVal CallV = state->getSVal(Callee);
-  const FunctionDecl *FD = CallV.getAsFunctionDecl();
-
+  const FunctionDecl *FD = C.getCalleeDecl(CE);
   if (!FD)
     return;
   
@@ -363,11 +360,8 @@
   if (CE->getNumArgs() != 1)
     return;
 
-  // Get the function declaration of the callee.
   const ProgramState *state = C.getState();
-  SVal X = state->getSVal(CE->getCallee());
-  const FunctionDecl *FD = X.getAsFunctionDecl();
-
+  const FunctionDecl *FD = C.getCalleeDecl(CE);
   if (!FD)
     return;