Fixed minor warnings with clang 13.

Makefile

@@ -61,11 +61,11 @@ ifdef HAVE_CLANG
 endif
 
 ifdef CLANG_WARNINGS
-  EXTRA_WARN=-Weverything -Wno-c++98-compat-pedantic \
+  EXTRA_WARN=-Weverything -Wno-c++98-compat-pedantic -Wno-unknown-warning-option \
     -Wno-switch-enum -Wno-conversion -Wno-covered-switch-default \
     -Wno-inconsistent-missing-destructor-override -Wno-float-equal \
     -Wno-exit-time-destructors -Wno-global-constructors -Wno-weak-vtables \
-    -Wno-four-char-constants -Wno-padded
+    -Wno-four-char-constants -Wno-padded -Wno-reserved-identifier
 
   CXXFLAGS+= $(EXTRA_WARN)
   CFLAGS+= $(EXTRA_WARN)

src/emucore/QuadTari.cxx

@@ -108,7 +108,7 @@ unique_ptr<Controller> QuadTari::addController(const Controller::Type type, bool
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool QuadTari::isFirst()
+bool QuadTari::isFirst() const
 {
   constexpr int MIN_CYCLES = 76; // minimal cycles required for stable input switch (just to be safe)
 

src/emucore/QuadTari.hxx

@@ -107,7 +107,7 @@ class QuadTari : public Controller
 
   private:
     // determine which controller is active
-    bool isFirst();
+    bool isFirst() const;
 
     unique_ptr<Controller> addController(const Controller::Type type, bool second);
 

src/gui/PlusRomsSetupDialog.cxx

@@ -47,7 +47,7 @@ void PlusRomsSetupDialog::loadConfig()
     const char* HEX_DIGITS = "0123456789ABCDEF";
     char id_chr[ID_LEN];
 
-    srand(time(NULL));
+    srand(time(nullptr));
     for(int i = 0; i < ID_LEN; i++)
       id_chr[i] = HEX_DIGITS[(rand() % 16)];