libnetconf2 UPDATE merge SSH and TLS req into one

In this commit I made the changes that if you want to use TLS, you have
to have both OpenSSL and libssh installed and viceversa. Set the minimum
required OpenSSL version to 3.0 and 0.9.5 for libssh.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6c08b01..98b4ad8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -90,9 +90,7 @@
 endif()
 option(ENABLE_EXAMPLES "Build examples" ON)
 option(ENABLE_COVERAGE "Build code coverage report from tests" OFF)
-option(ENABLE_SSH "Enable NETCONF over SSH support (via libssh)" ON)
-option(ENABLE_TLS "Enable NETCONF over TLS support (via OpenSSL)" ON)
-# option(ENABLE_SSH_TLS "Enable NETCONF over SSH and TLS support (via libssh and OpenSSL)" ON)
+option(ENABLE_SSH_TLS "Enable NETCONF over SSH and TLS support (via libssh and OpenSSL)" ON)
 option(ENABLE_DNSSEC "Enable support for SSHFP retrieval using DNSSEC for SSH (requires OpenSSL and libval)" OFF)
 set(READ_INACTIVE_TIMEOUT 20 CACHE STRING "Maximum number of seconds waiting for new data once some data have arrived")
 set(READ_ACTIVE_TIMEOUT 300 CACHE STRING "Maximum number of seconds for receiving a full message")
@@ -114,24 +112,19 @@
     src/session_client.c
     src/session_server.c
     src/server_config.c
-    src/server_config_ks.c
-    src/server_config_ts.c
     src/config_new.c)
 
-if(ENABLE_SSH)
+if(ENABLE_SSH_TLS)
     list(APPEND libsrc
         src/session_client_ssh.c
         src/session_server_ssh.c
-        src/config_new_ssh.c)
-    set(SSH_MACRO "#ifndef NC_ENABLED_SSH\n#define NC_ENABLED_SSH\n#endif")
-endif()
-
-if(ENABLE_TLS)
-    list(APPEND libsrc
+        src/config_new_ssh.c
         src/session_client_tls.c
         src/session_server_tls.c
-        src/config_new_tls.c)
-    set(TLS_MACRO "#ifndef NC_ENABLED_TLS\n#define NC_ENABLED_TLS\n#endif")
+        src/config_new_tls.c
+        src/server_config_ks.c
+        src/server_config_ts.c)
+    set(SSH_TLS_MACRO "#ifndef NC_ENABLED_SSH_TLS\n#define NC_ENABLED_SSH_TLS\n#endif")
 endif()
 
 set(headers
@@ -175,7 +168,7 @@
 #
 # checks
 #
-if(ENABLE_DNSSEC AND NOT ENABLE_SSH)
+if(ENABLE_DNSSEC AND NOT ENABLE_SSH_TLS)
     message(WARNING "DNSSEC SSHFP retrieval cannot be used without SSH support.")
     set(ENABLE_DNSSEC OFF)
 endif()
@@ -234,26 +227,17 @@
 set(CMAKE_REQUIRED_LIBRARIES pthread)
 check_function_exists(pthread_rwlockattr_setkind_np HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP)
 
-# dependencies - openssl
-if(ENABLE_TLS OR ENABLE_DNSSEC OR ENABLE_SSH)
+if(ENABLE_SSH_TLS)
+    # dependencies - openssl
     find_package(OpenSSL 3.0.0 REQUIRED)
-    if(ENABLE_TLS)
-        message(STATUS "OpenSSL found, required for TLS")
-        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DNC_ENABLED_TLS")
-    endif()
-
     target_link_libraries(netconf2 ${OPENSSL_LIBRARIES})
     include_directories(${OPENSSL_INCLUDE_DIR})
-endif()
 
-# dependencies - libssh
-if(ENABLE_SSH)
+    # dependencies - libssh
     find_package(LibSSH 0.9.5 REQUIRED)
-
     target_link_libraries(netconf2 ${LIBSSH_LIBRARIES})
     list(APPEND CMAKE_REQUIRED_LIBRARIES ${LIBSSH_LIBRARIES})
     include_directories(${LIBSSH_INCLUDE_DIRS})
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DNC_ENABLED_SSH")
 
     # crypt
     if(${CMAKE_SYSTEM_NAME} MATCHES "QNX")
@@ -282,6 +266,9 @@
     else()
         message(WARNING "LibPAM not found, PAM-based keyboard-interactive SSH server authentication method is disabled")
     endif()
+
+    # set compiler flag
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DNC_ENABLED_SSH_TLS")
 endif()
 
 # dependencies - libval
@@ -347,8 +334,8 @@
 
 # examples
 if(ENABLE_EXAMPLES)
-    if(NOT ENABLE_SSH)
-        message(WARNING "Examples will not be compiled because SSH is disabled.")
+    if(NOT ENABLE_SSH_TLS)
+        message(WARNING "Examples will not be compiled because SSH and TLS are disabled.")
     else()
         add_subdirectory(examples)
     endif()