Bug#18487951 - QUERY_CACHE_MIN_RES_UNIT SET TO ZERO, CRASHES IN QUERY_CACHE::FIND_BIN

Follow up patch to fix sys_vars.query_cache_min_res_unit_basic_32 test failure.

mysql-test/suite/sys_vars/r/query_cache_min_res_unit_basic_32.result

@@ -50,7 +50,7 @@ Warnings:
 Warning	1292	Truncated incorrect query_cache_min_res_unit value: '4294967296'
 SELECT @@global.query_cache_min_res_unit;
 @@global.query_cache_min_res_unit
-0
+4294967288
 SET @@global.query_cache_min_res_unit = 511;
 SELECT @@global.query_cache_min_res_unit;
 @@global.query_cache_min_res_unit
@@ -71,23 +71,23 @@ Warnings:
 Warning	1292	Truncated incorrect query_cache_min_res_unit value: '42949672950'
 SELECT @@global.query_cache_min_res_unit;
 @@global.query_cache_min_res_unit
-0
+4294967288
 SET @@global.query_cache_min_res_unit = ON;
 ERROR 42000: Incorrect argument type to variable 'query_cache_min_res_unit'
 SELECT @@global.query_cache_min_res_unit;
 @@global.query_cache_min_res_unit
-0
+4294967288
 SET @@global.query_cache_min_res_unit = 'test';
 ERROR 42000: Incorrect argument type to variable 'query_cache_min_res_unit'
 SELECT @@global.query_cache_min_res_unit;
 @@global.query_cache_min_res_unit
-0
+4294967288
 '#-------------------FN_DYNVARS_132_05----------------------------#'
 SET @@session.query_cache_min_res_unit = 0;
 ERROR HY000: Variable 'query_cache_min_res_unit' is a GLOBAL variable and should be set with SET GLOBAL
 SELECT @@query_cache_min_res_unit;
 @@query_cache_min_res_unit
-0
+4294967288
 '#----------------------FN_DYNVARS_132_06------------------------#'
 SELECT @@global.query_cache_min_res_unit = VARIABLE_VALUE 
 FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES