Fix test failures in variables-big in --embedded.

Problem was the use of SHOW PROCESSLIST. This is not fully functional in
embedded server, STATE is hardcoded to "Writing to net".

Fixed using --replace_result for STATE.

mysql-test/t/variables-big.test

@@ -38,18 +38,24 @@
 --disable_warnings
 SET SESSION transaction_prealloc_size=1024*1024*1024*1;
 --replace_column 1 <Id> 6 <Time>
+# Embedded server is hardcoded to show "Writing to net" as STATE.
+--replace_result "Writing to net" "NULL"
 SHOW PROCESSLIST;
 SET SESSION transaction_prealloc_size=1024*1024*1024*2;
 --replace_column 1 <Id> 6 <Time>
+--replace_result "Writing to net" "NULL"
 SHOW PROCESSLIST;
 SET SESSION transaction_prealloc_size=1024*1024*1024*3;
 --replace_column 1 <Id> 6 <Time>
+--replace_result "Writing to net" "NULL"
 SHOW PROCESSLIST;
 SET SESSION transaction_prealloc_size=1024*1024*1024*4;
 --replace_column 1 <Id> 6 <Time>
+--replace_result "Writing to net" "NULL"
 SHOW PROCESSLIST;
 SET SESSION transaction_prealloc_size=1024*1024*1024*5;
 --replace_column 1 <Id> 6 <Time>
+--replace_result "Writing to net" "NULL"
 SHOW PROCESSLIST;
 --enable_warnings