The rom line renderer upper-cased every crc, so Dinothawr.zip's
683ed4ad, the one lower-case crc libretro writes, changed with no
correction behind it. A line whose values match ours now keeps its
bytes, a corrected crc follows the case of its own line, and an added
line keeps the file's upper case. An empty truth hands System.dat back
byte for byte for RetroArch and Lakka.