after innodb/xtradb merge: use the correct visibility for internal functions

otherwise innodb plugin might invoke xtradb function with the same name,
and that might crash (./mtr --emb innodb.strict_mode)

storage/innobase/handler/ha_innodb.cc

@@ -12262,7 +12262,7 @@ innobase_convert_to_filename_charset(
 
 /**********************************************************************
 Issue a warning that the row is too big. */
-extern "C"
+extern "C" UNIV_INTERN
 void
 ib_warn_row_too_big(const dict_table_t*	table)
 {

storage/xtradb/handler/ha_innodb.cc

@@ -13988,7 +13988,7 @@ innobase_convert_to_filename_charset(
 
 /**********************************************************************
 Issue a warning that the row is too big. */
-extern "C"
+extern "C" UNIV_INTERN
 void
 ib_warn_row_too_big(const dict_table_t*	table)
 {