DP2ADD is valid on pshaders 2.0 and above, has 4 parameters.
TEXLDD is valid on pshaders 2.x and above, has 5 parameters.

There are a total of 17 instructions without a destination token. Of
those 9 have num_params != 0, which means that we will not process any
of them correctly, because we assume the first token (if present) is a
destination token.

Those are basically all the flow control instructions, which we plan to
support very soon. They have source tokens, and no destination. Add a
flag that marks them up to the ins table. Use this flag in the trace
pass, and generation pass.

GLSL uniforms have as scope the entire program.
To prevent conflicts, name pshader and vshader constants differently.
Based on a patch by Jason Green.