also check errno when lseek64 returns -1

[karas84]

Pull Request checklist

Note: these are not necessarily requirements

• [x] I reformatted the code with clang-format
• [x] I checked to make sure my submission worked
• [x] I am the author of submission or have permission from the original author
• [ ] Requires update of the PS2SDK or other dependencies
• [ ] Others (please specify below)

Pull Request description

in genLseek the return value of lseek64 is checked against the error value -48 but it should also check against the -1 return code and the value 48 in errno. This fixes #116 allowing PS2 games to boot using PS2Disc.