Make the type checks in IntrusiveList a little less strict
Make the type checks in IntrusiveList a little less strict

There's no point in checking whether U is convertible to T is these are
the same types. Otherwise static assertion may fail for classes with
non-inline constructors.
CezaryGapinski/distortos,jasmin-j/distortos,DISTORTEC/distortos,CezaryGapinski/distortos,jasmin-j/distortos,DISTORTEC/distortos,CezaryGapinski/distortos,jasmin-j/distortos,CezaryGapinski/distortos,jasmin-j/distortos,DISTORTEC/distortos,DISTORTEC/distortos,jasmin-j/distortos,CezaryGapinski/distortos