Nim: `encoding: ASCII` does not work on Windows

[generalmimon]

Cc @sealmove

On my machine, the error looks like this:

C:\temp\kaitai_struct\tests\spec\nim\texpr_str_encodings.nim(7) texpr_str_encodings
C:\temp\kaitai_struct\tests\compiled\nim\expr_str_encodings.nim(122) fromFile
C:\temp\kaitai_struct\tests\compiled\nim\expr_str_encodings.nim(50) read
C:\temp\kaitai_struct\runtime\nim\kaitai_struct_nim_runtime.nim(332) encode
C:\Users\pp\.choosenim\toolchains\nim-1.6.4\lib\pure\encodings.nim(505) convert
C:\Users\pp\.choosenim\toolchains\nim-1.6.4\lib\pure\encodings.nim(354) open
Error: unhandled exception: cannot find encoding ASCII [EncodingError]

As I see in encodings.nim:338-355, the encoding is resolved differently on Windows. On non-Windows systems, apparently iconv is used, but on Windows the code uses a winEncodings lookup table for name and the corresponding code page number, and there's no ascii.

[sealmove]

Hello @generalmimon. It looks like there is an entry for us-ascii but not for ascii. The issue should be resolved now with e0caf5. Please confirm, cheers.

[generalmimon]

@sealmove Thanks for the fix, it works fine except that cmpIgnoreCase returns int, not bool: kaitai-io/kaitai_struct_nim_runtime@a3253fd

This issue is now solved.