libc: fix isspace() implementation per gbl08ma
libc: fix isspace() implementation per gbl08ma

https://github.com/Jonimoose/libfxcg/issues/6

Forty-Bot/libfxcg,Forty-Bot/libfxcg,Jonimoose/libfxcg,ComputerNerd/libfxcg-copyleft,ComputerNerd/libfxcg-copyleft,ComputerNerd/libfxcg-copyleft,Jonimoose/libfxcg,Forty-Bot/libfxcg,Forty-Bot/libfxcg,ComputerNerd/libfxcg-copyleft,Jonimoose/libfxcg