Narrow compiler/options for skipping testcornerstoragerefwrap

We now only skip if

• The compiler is gcc 8.2.*
• The compile options include -ftree-loop-vectorize (possibly implicitly due to -O3)

We also complain loudly during cmake configure run, as this issue might miscompile other code than just the test.

Closes: #19 (closed), #21 (closed)