- enable_extras 'm_ssl_gnutls.cpp' unless system 'gnutls-cli --version >/dev/null 2>&1';
- enable_extras 'm_ssl_openssl.cpp' unless system 'openssl --version >/dev/null 2>&1';
+ enable_extras 'm_ssl_gnutls.cpp' unless system 'pkg-config --exists gnutls >/dev/null 2>&1';
+ enable_extras 'm_ssl_mbedtls.cpp' if -e '/usr/include/mbedtls/ssl.h';
+ enable_extras 'm_ssl_openssl.cpp' unless system 'pkg-config --exists openssl >/dev/null 2>&1';