cmake: fix warnings when PLUGIN_MROONGA=NO

storage/mroonga/CMakeLists.txt

@@ -392,11 +392,9 @@ else()
 endif()
 
 if(GROONGA_NORMALIZER_MYSQL_FOUND)
-  set_property(TARGET mroonga APPEND PROPERTY
-    COMPILE_DEFINITIONS "WITH_GROONGA_NORMALIZER_MYSQL=1")
+  add_definitions("-DWITH_GROONGA_NORMALIZER_MYSQL=1")
   if(MRN_GROONGA_NORMALIZER_MYSQL_EMBED)
-    set_property(TARGET mroonga APPEND PROPERTY
-      COMPILE_DEFINITIONS "MRN_GROONGA_NORMALIZER_MYSQL_EMBEDDED")
+    add_definitions("-DMRN_GROONGA_NORMALIZER_MYSQL_EMBEDDED")
   else()
     set_property(TARGET mroonga APPEND PROPERTY
       COMPILE_DEFINITIONS "GROONGA_NORMALIZER_MYSQL_PLUGIN_NAME=\"normalizers/mysql\"")
@@ -404,8 +402,7 @@ if(GROONGA_NORMALIZER_MYSQL_FOUND)
 endif()
 
 if(MRN_GROONGA_EMBED)
-  set_property(TARGET mroonga APPEND PROPERTY
-    COMPILE_DEFINITIONS "MRN_GROONGA_EMBEDDED")
+  add_definitions("-DMRN_GROONGA_EMBEDDED")
 endif()
 
 set(MRN_DEFAULT_PARSER "" CACHE STRING