CTestCustom: Suppress MIPSpro warnings about Olimit

Since we compile command implementations in large batches the
translation units get too big for MIPSpro optimization limits.
Suppress the warnings it produces:

 Warning: Olimit was exceeded on function ...
 Warning: To override Olimit for all functions in file, use -OPT:Olimit=3201
Merge topic 'update-warning-suppression' into next

87d66066 CTestCustom: Suppress MIPSpro warnings about Olimit