A bare-metal library supplying functions rustc may lower code to.
This library is not intended for general use, and is superseded by a system libc if one is available. In a freestanding context, however, common functions such as memset, memcpy, etc. are not implemented. This library provides an implementation of these functions which are either required by libcore or called by rustc implicitly.
This library is never included by default, and must be manually included if necessary. It is an error to include this library when also linking with the system libc library.