Remove the unused dllname parameter to the trace function
Make a function typedef actually use the right type

All functions that are assigned to function pointers with this
typedef (WelsHadamardQuant2x2Skip_c and WelsHadamardQuant2x2Skip_mmx)
use int32_t instead of BOOL_T for the return value.
Remove an unnecessary cast when setting function pointers

By removing the casts we make sure that the function signature
actually matches and isn't silenced by the cast.
Make the function signatures actually match when used as function pointer

Hiding the function signature mismatch with a cast can lead to
more concrete breakage being missed.
Merge pull request #206 from mstorsjo/function-pointer-cleanup

Avoid mismatches in function pointer assignments
Merge pull request #205 from mstorsjo/cleanup-trace

Remove the unused dllname parameter to the trace function