Function unmap

lib-src/lv2/serd/src/string.c:173–173

	"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$";

static inline uint8_t unmap(const uint8_t in) { return b64_unmap[in] - 47; }

/**
   Decode 4 base64 characters to 3 raw bytes.