libnetconf2: Update to 0.12-r2

Cleaned up Makefile slightly. The removed CMAKE_OPTIONS are defaults from
cmake.mk

Removed Upstreamed patches.

Rebased and added .patch to the remaining one.

Added -Wformat-security patch.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

libs/libnetconf2/patches/001-fix-pthread-error.patch

@@ -0,0 +1,38 @@
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -176,6 +176,7 @@ target_link_libraries(netconf2 ${CMAKE_THREAD_LIBS_INIT})
+ set(CMAKE_REQUIRED_LIBRARIES pthread)
+ check_include_file(stdatomic.h HAVE_STDATOMIC)
+ check_function_exists(pthread_mutex_timedlock HAVE_PTHREAD_MUTEX_TIMEDLOCK)
++check_function_exists(pthread_rwlockattr_setkind_np HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP)
+ 
+ # dependencies - openssl
+ if(ENABLE_TLS OR ENABLE_DNSSEC OR ENABLE_SSH)
+--- a/src/config.h.in
++++ b/src/config.h.in
+@@ -73,4 +73,7 @@
+  */
+ #define NC_PS_QUEUE_SIZE @MAX_PSPOLL_THREAD_COUNT@
+ 
++/* Portability feature-check macros. */
++#cmakedefine HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP
++
+ #endif /* NC_CONFIG_H_ */
+--- a/src/session_server.c
++++ b/src/session_server.c
+@@ -560,6 +560,7 @@ nc_server_init(struct ly_ctx *ctx)
+     errno=0;
+ 
+     if (pthread_rwlockattr_init(&attr) == 0) {
++#if defined(HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP)
+         if (pthread_rwlockattr_setkind_np(&attr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP) == 0) {
+             if (pthread_rwlock_init(&server_opts.endpt_lock, &attr) != 0) {
+                 ERR("%s: failed to init rwlock(%s).", __FUNCTION__, strerror(errno));
+@@ -570,6 +571,7 @@ nc_server_init(struct ly_ctx *ctx)
+         } else {
+             ERR("%s: failed set attribute (%s).", __FUNCTION__, strerror(errno));
+         }
++#endif
+         pthread_rwlockattr_destroy(&attr);
+     } else {
+         ERR("%s: failed init attribute (%s).", __FUNCTION__, strerror(errno));