GopenPGP, an open source encryption library for native applications 7 years ago
The instructions aren't very straightforward, but you can compile Go code (which GopenPGP is) into a C archive https://golang.org/cmd/go/#hdr-Build_modes
[ my public key: https://keybase.io/tblyler; my proof: https://keybase.io/tblyler/sigs/-IhKSqSL6XKOIcYsO5tw-58dCOm89j8_89Fo1GyLoDg ]