Auto merge of #103836 - H4x5:extra-float-constants, r=thomcc

Add additional float constants

Initial implementation of this ACP: rust-lang/libs-team#119. [Accepted]
Tracking issue: #103883

The values for the constants are copied from the [`libstdc++` source code](https://github.com/gcc-mirror/gcc/blob/16e2427f50c208dfe07d07f18009969502c25dc8/libstdc%2B%2B-v3/include/std/numbers#L57-L120).

Author: bors