You've been heavily downvoted because you made a category error. GlibC, musl, and uclibc are implementations of the c standard library[1]. Glib[2], this, and NSPR[3] (among others), on the other hand, abstract away platform-specific things. So whereas strcpy is a standard function that you can count on being there, the process for opening a window is different on windows, mac (quartz), mac (cocoa), unix (x11), unix (wayland), and others; the cross-platform libraries handle this and provide you with a single api for (for example) opening a window.
Now, as a language developer, you actually don't have to worry about any of these. The c standard library will be provided by the os and you don't have to think about it. Some programming languages that want to replace c don't rely on the c standard library, but you shouldn't have to worry about that. As for abstracting out different platform apis, I would say that doesn't really belong in your language itself.
Now, as a language developer, you actually don't have to worry about any of these. The c standard library will be provided by the os and you don't have to think about it. Some programming languages that want to replace c don't rely on the c standard library, but you shouldn't have to worry about that. As for abstracting out different platform apis, I would say that doesn't really belong in your language itself.
1: https://en.wikipedia.org/wiki/C_standard_library
2: https://developer.gnome.org/glib/
3: https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NS...