Fix hw detection more

Fix hw detection more

gmx_hardware_detect was called in response to GoogleTest environment
SetUp function, so the cleanup for its global should occur in response
to the corresponding TearDown function. Both those should be virtual.
Thus the hardwareInfo should not be in a smart pointer called by a
destructor that might be called at a different point from TearDown.

The new getter function and the callback that handles making the first
call to it conform better to GoogleTest's recommendation to arrange to
call AddGlobalTestEnvironment from main() rather than rely on static
initialization.

Made hardwareInit a non-member function because that improves
encapsulation.

Change-Id: I2f8e14ecc1707bf31d023a4eb4fea0a20543910b