Fixed handling of exec timeout in sub_test.
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Merge pull request #765 from vasslitvinov/fix-exectimeout-in-sub_test

Fixed the handling of test execution timeout in sub_test.

When a test with multiple execopts settings timed out under
one of those setting, the later execopts settings would still run
but would not be diff-ed against .good or reported as a success or a failure.
This change fixes that.

The bug was due to the following. The variable 'exectimeout' was used
roughly as follows:

for testname in testsrc:
    exectimeout = False
    for compopts in compoptslist:
        for texecopts in execoptslist:
            for count in xrange(numTrials):
                ... if there is a timeout:
                        exectimeout = True
                if not exectimeout:
                    ... run prediffs ...
                    ... report test success or failure ... 
                if perftest:
                    if exectimeout or status != 0:
                        break

So 'exectimeout = False' was due at the top of the loop body of
either 'for count' or 'for texecopts'.

I chose to put it at the top of 'for count' - the innermost loop
that launches test execution.

The 'exectimeout = False' at the top of the 'for testname' loop
needs to be removed - this will be my upcoming separate PR.