gallivm: increase size of texture target enum bitfield

Need to bump up the size of texture target bitfield for MSVC.

Fixes: 0ce7c4a7c9 ("gallivm: Use the proper enum for the texture target bitfield.")

Reviewed-by: Neha Bhende <bhenden@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9928>

src/gallium/auxiliary/gallivm/lp_bld_sample.h

@@ -169,7 +169,7 @@ struct lp_static_texture_state
    unsigned swizzle_a:3;
 
    /* pipe_texture's state */
-   enum pipe_texture_target target:4;        /**< PIPE_TEXTURE_* */
+   enum pipe_texture_target target:5;        /**< PIPE_TEXTURE_* */
    unsigned pot_width:1;     /**< is the width a power of two? */
    unsigned pot_height:1;
    unsigned pot_depth:1;