MXS-862: Create common MySQL library

The MySQLCommon library contains functions used by both the protocol and
authenticator modules. The contents of the modutil.c file could also be
moved to this file if the functions in that file are only used by modules
and not the core.

server/modules/protocol/MySQL/CMakeLists.txt

@@ -0,0 +1,7 @@
+add_library(MySQLCommon SHARED mysql_common.c)
+target_link_libraries(MySQLCommon maxscale-common)
+set_target_properties(MySQLCommon PROPERTIES VERSION "2.0.0")
+install_module(MySQLCommon core)
+
+add_subdirectory(MySQLBackend)
+add_subdirectory(MySQLClient)

server/modules/protocol/MySQL/MySQLBackend/CMakeLists.txt

@@ -0,0 +1,7 @@
+add_library(MySQLBackend SHARED mysql_backend.c)
+# TODO: Refactor MySQLBackend so that COM_CHANGE_USER processing is
+# transparent to the protocol module. After this change, we don't need to
+# link against MySQLAuth.
+target_link_libraries(MySQLBackend maxscale-common MySQLCommon MySQLAuth)
+set_target_properties(MySQLBackend PROPERTIES VERSION "2.0.0")
+install_module(MySQLBackend core)

server/modules/protocol/MySQL/MySQLClient/CMakeLists.txt

@@ -0,0 +1,4 @@
+add_library(MySQLClient SHARED mysql_client.c)
+target_link_libraries(MySQLClient maxscale-common  MySQLCommon)
+set_target_properties(MySQLClient PROPERTIES VERSION "1.0.0")
+install_module(MySQLClient core)