wined3d: Move _shader_program_dump_decl_usage() into baseshader.c

[Jason Green]

Both pixel and vertex shaders use an identical function to display
debug traces of the D3DSIO_DCL opcode.  This consolidates them into a
single function in the new baseshader.c file.  Also, they were passing
a reference to their interface previously which never not used, so
that has been removed.

This requires Ivan's initial baseshader.c patch as a minimum, and
should be a no-op.