crt: Define fseeko and ftello symbols as aliases to fseek and ftell

Both msvcrt and UCRT ABI uses for off_t-based function without any suffix
in their name the 32-bit long off_t type for both 32-bit and 64-bit
architectures.

So define the fseeko symbol as alias to fseek and ftello symbol as alias to
ftell symbol because the fseek and ftell also uses only 32-bit offset type.

Signed-off-by: Martin Storsjö <martin@martin.st>