i965: fix 1D texture borders with GL_CLAMP_TO_BORDER

i965: fix 1D texture borders with GL_CLAMP_TO_BORDER

With 1D textures, GL_TEXTURE_WRAP_T should be ignored (only
GL_TEXTURE_WRAP_S should be respected).  But the i965 hardware
seems to follow the value of GL_TEXTURE_WRAP_T even when sampling
1D textures.

This fix forces GL_TEXTURE_WRAP_T to be GL_REPEAT whenever 1D
textures are used; this allows the texture to be sampled
correctly, avoiding "imaginary" border elements in the T direction.

This bug was demonstrated in the Piglit tex1d-2dborder test.
With this fix, that test passes.