Crystal: spec fails on alpine linux because of iconv

[mosop]

spec/std/string.cr and spec/std/io/io_spec.cr fail on alpine linux. Because musl libc iconv_open does not support GB2312 as a "to" argument.

For example, the below code fails.

"好".encode("GB2312") # => raises "invalid encoding: GB2312"

FYI, as the musl source, EUC_JP (0320) or greater is not supported as a target encoding.

#define UTF_32BE    0300
#define UTF_16LE    0301
#define UTF_16BE    0302
#define UTF_32LE    0303
#define UCS2BE      0304
#define UCS2LE      0305
#define WCHAR_T     0306
#define US_ASCII    0307
#define UTF_8       0310
#define EUC_JP      0320
#define SHIFT_JIS   0321
#define GB18030     0330
#define GBK         0331
#define GB2312      0332
#define BIG5        0340
#define EUC_KR      0350

[rdp]

Maybe the specs could convert to some other more common encoding?

[straight-shoota]

That sounds reasonable.