settings, yuzu qt: Add migration code for CPU accuracy

Old CPU Accuracy setting won't translate well into since we're adding
one at the beginning of the list. On first boot with the new setting,
just use the default setting.

src/common/settings.h

@@ -286,6 +286,8 @@ struct Values {
 
     // Cpu
     Setting<CPUAccuracy> cpu_accuracy{CPUAccuracy::Auto, "cpu_accuracy"};
+    // TODO: remove cpu_accuracy_first_time, migration setting added 8 July 2021
+    BasicSetting<bool> cpu_accuracy_first_time{true, "cpu_accuracy_first_time"};
 
     BasicSetting<bool> cpuopt_page_tables{true, "cpuopt_page_tables"};
     BasicSetting<bool> cpuopt_block_linking{true, "cpuopt_block_linking"};

src/yuzu/configuration/config.cpp

@@ -793,7 +793,13 @@ void Config::ReadPathValues() {
 void Config::ReadCpuValues() {
     qt_config->beginGroup(QStringLiteral("Cpu"));
 
-    ReadGlobalSetting(Settings::values.cpu_accuracy);
+    ReadBasicSetting(Settings::values.cpu_accuracy_first_time);
+    if (Settings::values.cpu_accuracy_first_time) {
+        Settings::values.cpu_accuracy.SetValue(Settings::values.cpu_accuracy.GetDefault());
+        Settings::values.cpu_accuracy_first_time.SetValue(false);
+    } else {
+        ReadGlobalSetting(Settings::values.cpu_accuracy);
+    }
 
     ReadGlobalSetting(Settings::values.cpuopt_unsafe_unfuse_fma);
     ReadGlobalSetting(Settings::values.cpuopt_unsafe_reduce_fp_error);
@@ -1309,6 +1315,7 @@ void Config::SavePathValues() {
 void Config::SaveCpuValues() {
     qt_config->beginGroup(QStringLiteral("Cpu"));
 
+    WriteBasicSetting(Settings::values.cpu_accuracy_first_time);
     WriteSetting(QStringLiteral("cpu_accuracy"),
                  static_cast<u32>(Settings::values.cpu_accuracy.GetValue(global)),
                  static_cast<u32>(Settings::values.cpu_accuracy.GetDefault()),