[clang] [analyzer] Conversion to CheckerFamily: DereferenceChecker (PR #150442)

[Donát Nagy via cfe-commits]

================
@@ -25,18 +25,22 @@ using namespace clang;
 using namespace ento;
 
 namespace {
+
+class DerefBugType : public BugType {
+  StringRef ArrayMsg, FieldMsg;
+
+public:
+  DerefBugType(CheckerFrontend *FE, StringRef Desc, const char *RMsg,
+               const char *FMsg = nullptr)
+      : BugType(FE, Desc), ArrayMsg(RMsg), FieldMsg(FMsg ? FMsg : RMsg) {}
----------------
NagyDonat wrote:

```suggestion
  DerefBugType(CheckerFrontend *FE, StringRef Desc, const char *AMsg,
               const char *FMsg = nullptr)
      : BugType(FE, Desc), ArrayMsg(AMsg), FieldMsg(FMsg ? FMsg : AMsg) {}
```
The field `ArrayMsg` was previously called `RegularMsg` and the name `RMsg` was a remnant of this. For the sake of consistency I'm updating it here.

https://github.com/llvm/llvm-project/pull/150442