[analyzer][NFC] Remove dead field of UnixAPICheckers

Initially, I thought there is some fundamental bug here by not using the
bool fields, but it turns out D55425 split this checker into two
separate ones; making these fields dead.

Depends on D127836, which uncovered this issue.

Reviewed By: martong

Differential Revision: https://reviews.llvm.org/D127838

clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp

@@ -43,8 +43,6 @@ class UnixAPIMisuseChecker : public Checker< check::PreStmt<CallExpr> > {
   mutable Optional<uint64_t> Val_O_CREAT;
 
 public:
-  bool CheckMisuse = false, CheckPortability = false;
-
   void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
 
   void CheckOpen(CheckerContext &C, const CallExpr *CE) const;
@@ -503,7 +501,7 @@ void UnixAPIPortabilityChecker::checkPreStmt(const CallExpr *CE,
     mgr.registerChecker<CHECKERNAME>();                                        \
   }                                                                            \
                                                                                \
-  bool ento::shouldRegister##CHECKERNAME(const CheckerManager &mgr) {              \
+  bool ento::shouldRegister##CHECKERNAME(const CheckerManager &mgr) {          \
     return true;                                                               \
   }