Apply character encoding conversion to hard-coded strings

This fixes an issue where menu items like "戻る" were garbled in Unicode
mode.

src/sys/nact.cpp

@@ -23,8 +23,8 @@ NACT::NACT(int sys_ver, uint32 crc32_a, uint32 crc32_b, const Config& config)
 	: sys_ver(sys_ver),
 	  crc32_a(crc32_a),
 	  crc32_b(crc32_b),
-	  lang(get_language()),
-	  encoding(Encoding::create(get_encoding_name(config)))
+	  encoding(Encoding::create(get_encoding_name(config))),
+	  strings(get_language(), encoding.get())
 {
 	platform_initialize();