Relax an assertion. Various cases could lead to non-symbol values.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@103707 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Checker/MallocChecker.cpp

@@ -182,7 +182,10 @@ const GRState *MallocChecker::FreeMemAux(CheckerContext &C, const CallExpr *CE,
     return state;
 
   SymbolRef Sym = ArgVal.getAsLocSymbol();
-  assert(Sym);
+
+  // Various cases could lead to non-symbol values here.
+  if (!Sym)
+    return state;
 
   const RefState *RS = state->get<RegionState>(Sym);