FindGnuTLS

Попробуйте найти библиотеку GNU Transport Layer Security (gnutls)

После завершения этого будет определено

GNUTLS_FOUND - System has gnutls
GNUTLS_INCLUDE_DIR - The gnutls include directory
GNUTLS_LIBRARIES - The libraries needed to use gnutls
GNUTLS_DEFINITIONS - Compiler switches required for using gnutls