(partially) Fix Bug#55227 Fix compiler warnings in innodb with gcc 4.6

Fix compiler warning:
handler/i_s.cc: In function 'int trx_i_s_common_fill_table(THD*, TABLE_LIST*, COND*)':
handler/i_s.cc:931:8: error: variable 'ret' set but not used [-Werror=unused-but-set-variable]

storage/innodb_plugin/handler/i_s.cc

@@ -1013,6 +1013,7 @@ trx_i_s_common_fill_table(
 	see http://bugs.mysql.com/29900 ; when that bug is resolved
 	we can enable the DBUG_RETURN(ret) above */
 	DBUG_RETURN(0);
+	ret++;  // silence a gcc46 warning
 #endif
 }