Allow enabling GBA RTC regardless of rom types

- Add core option to allow RTC to be enabled regardless of rom. This usuable for rom patches that requires the RTC to be enabled yet the RTC flag is not enabled. (aka Pokemon patches)

src/libretro/libretro.cpp

@@ -56,6 +56,7 @@ static EmulatedSystem* core = NULL;
 static IMAGE_TYPE type = IMAGE_UNKNOWN;
 static unsigned current_gbPalette = 0;
 static bool opt_colorizer_hack = false;
+static bool opt_forceRTCenable = false;
 
 uint16_t systemColorMap16[0x10000];
 uint32_t systemColorMap32[0x10000];
@@ -801,6 +802,9 @@ static void load_image_preferences(void)
     if (flashSize == SIZE_FLASH512 || flashSize == SIZE_FLASH1M)
         flashSetSize(flashSize);
 
+    if (opt_forceRTCenable)
+        rtcEnabled = true;
+
     rtcEnable(rtcEnabled);
 
     // game code starting with 'R' or 'V' has rumble support
@@ -1059,6 +1063,14 @@ static void update_variables(bool startup)
         usebios = newval;
     }
 
+    var.key = "vbam_forceRTCenable";
+    var.value = NULL;
+
+    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value) {
+        bool newval = (strcmp(var.value, "enabled") == 0) ? true : false;
+        opt_forceRTCenable = newval;
+    }
+
     var.key = "vbam_solarsensor";
     var.value = NULL;
 
@@ -1221,11 +1233,12 @@ static void update_variables(bool startup)
             "vbam_showborders",
             "vbam_gbcoloroption"
         };
-        char gba_options[4][22] = {
+        char gba_options[5][22] = {
             "vbam_solarsensor",
             "vbam_sound_5",
             "vbam_sound_6",
-            "vbam_gyro_sensitivity"
+            "vbam_gyro_sensitivity",
+            "vbam_forceRTCenable"
         };
 
         // Show or hide GB/GBC only options
@@ -1238,7 +1251,7 @@ static void update_variables(bool startup)
 
         // Show or hide GBA only options
         option_display.visible = (type == IMAGE_GBA) ? 1 : 0;
-        for (i = 0; i < 4; i++)
+        for (i = 0; i < 5; i++)
         {
             option_display.key = gba_options[i];
             environ_cb(RETRO_ENVIRONMENT_SET_CORE_OPTIONS_DISPLAY, &option_display);

src/libretro/libretro_core_options.h

@@ -58,6 +58,17 @@ struct retro_core_option_definition option_defs_us[] = {
         },
         "disabled"
     },
+    {
+        "vbam_forceRTCenable",
+        "Force enable RTC",
+        "Forces the internal real-time clock to be enabled regardless of rom. Usuable for rom patches that requires clock to be enabled (aka Pokemon).",
+        {
+            { "disabled",  NULL },
+            { "enabled",   NULL },
+            { NULL, NULL },
+        },
+        "disabled"
+    },
     {
         "vbam_soundinterpolation",
         "Sound Interpolation",