Remove C-style 'srand()' and use our already existing 'Random' class.

This also fixes a warning of NULL vs. nullptr.

src/emucore/OSystem.cxx

@@ -516,16 +516,15 @@ string OSystem::createConsole(const FilesystemNode& rom, const string& md5sum,
       // Make sure there always is an id
       if(settings().getString("plusroms.id") == EmptyString)
       {
-        const int ID_LEN = 32 - 2; // WE prefix added later
+        constexpr int ID_LEN = 32 - 2; // WE prefix added later
         const char* HEX_DIGITS = "0123456789ABCDEF";
         char id_chr[ID_LEN] = {0};
 
-        srand(time(NULL));
-        for(int i = 0; i < ID_LEN; i++)
-          id_chr[i] = HEX_DIGITS[(rand() % 16)];
+        Random rnd;
+        for(char& c: id_chr)
+          c = HEX_DIGITS[rnd.next() % 16];
 
-        std::string id_str(id_chr, ID_LEN);
-        settings().setValue("plusroms.id", id_str);
+        settings().setValue("plusroms.id", string(id_chr, ID_LEN));
       }
 
       myEventHandler->changeStateByEvent(Event::PlusRomsSetupMode);

src/emucore/Random.hxx

@@ -18,6 +18,8 @@
 #ifndef RANDOM_HXX
 #define RANDOM_HXX
 
+#include <chrono>
+
 #include "bspf.hxx"
 #include "Serializable.hxx"
 
@@ -32,7 +34,14 @@ class Random : public Serializable
 {
   public:
     /**
-      Create a new random number generator
+      Create a new random number generator with seed based on system time.
+    */
+    explicit Random() {
+      initSeed(std::chrono::system_clock::now().time_since_epoch().count());
+    }
+
+    /**
+      Create a new random number generator with given seed.
     */
     explicit Random(uInt32 seed) { initSeed(seed); }
 
@@ -46,7 +55,7 @@ class Random : public Serializable
     }
 
     /**
-      Answer the next random number from the random number generator
+      Answer the next random number from the random number generator.
 
       @return A random number
     */
@@ -107,7 +116,6 @@ class Random : public Serializable
 
   private:
     // Following constructors and assignment operators not supported
-    Random() = delete;
     Random(const Random&) = delete;
     Random(Random&&) = delete;
     Random& operator=(const Random&) = delete;