Revert "ir_to_mesa: Load all the STATE_VAR elements of a builtin uniform to a temp."

Revert "ir_to_mesa: Load all the STATE_VAR elements of a builtin uniform to a temp."

This reverts commit 5ad74779cea07cc6a19a52874cdaef8b018e2f1b.

Sorry, but I had to revert this.

Any commit which needlessly increases the number of temporaries is wrong.
More temporaries mean less shader performance because of reduced parallelism
and therefore less efficient latency hiding. In this case, there is possible
performance degradation of every shader which uses GL state variables.
I cannot accept this.