Fix generating the unit test wrappers when building with MingW32
Fix generating the unit test wrappers when building with MingW32

For some reason the unit test symbols end up in the read-only data
section when building on windows rather than the initialised data
section so they have a different letter in the list generated by nm.
They also begin with an underscore because windows likes to add
underscores to symbols for some reason. This patch changes the regular
expressions in the code to generate the wrapper list so that it
accepts either way.

Reviewed-by: Robert Bragg <12e9293ec6b30c7fa8a0926af42807e929c1684f@linux.intel.com>

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