MDEV-11660 Make encryption plugins "pure"

Do not exporting mysqld entry points directly.
This is needed for mariabackup, to load encryption plugins on Windows.

All plugins are "pure" by default. To mark plugin "impure"
it should use RECOMPILE_FOR_EMBEDDED or STORAGE_ENGINE keyword.

Author: vaintroub

cmake/plugin.cmake

@@ -201,13 +201,15 @@ MACRO(MYSQL_ADD_PLUGIN)
     # executable to the linker command line (it would result into link error). 
     # Thus we skip TARGET_LINK_LIBRARIES on Linux, as it would only generate
     # an additional dependency.
-    IF(NOT ARG_CLIENT)
+    IF(ARG_RECOMPILE_FOR_EMBEDDED OR ARG_STORAGE_ENGINE)
       IF(MSVC)
         ADD_DEPENDENCIES(${target} gen_mysqld_lib)
         TARGET_LINK_LIBRARIES(${target} mysqld_import_lib)
       ELSEIF(NOT CMAKE_SYSTEM_NAME STREQUAL "Linux")
         TARGET_LINK_LIBRARIES (${target} mysqld)
       ENDIF()
+    ELSEIF(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+      TARGET_LINK_LIBRARIES (${target} "-Wl,--no-undefined")
     ENDIF()
 
     IF(ARG_LINK_LIBRARIES)

mysql-test/suite/encryption/r/filekeys_syntax.result

@@ -28,7 +28,7 @@ select plugin_status from information_schema.plugins
 where plugin_name = 'file_key_management';
 plugin_status
 install soname 'file_key_management';
-ERROR HY000: Invalid key id at MYSQL_TMP_DIR/keys.txt line 2, column 11
+ERROR HY000: Invalid key id at MYSQL_TMP_DIR/keys.txt line 2, column 10
 call mtr.add_suppression("Invalid key id");
 call mtr.add_suppression("Plugin 'file_key_management' init function returned error");
 call mtr.add_suppression("Plugin 'file_key_management' registration.*failed");

plugin/auth_dialog/CMakeLists.txt

@@ -15,5 +15,8 @@
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
 
 ADD_DEFINITIONS(-DNO_GET_TTY_PASSWORD)
+IF(LIBDL)
+  SET(LLDL LINK_LIBRARIES dl)
+ENDIF()
 MYSQL_ADD_PLUGIN(dialog dialog.c ${CMAKE_SOURCE_DIR}/libmysql/get_password.c
-  MODULE_ONLY CLIENT COMPONENT ClientPlugins)
+  MODULE_ONLY CLIENT ${LLDL} COMPONENT ClientPlugins)