draw: silence MSVC signed/unsigned comparison warnings

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

src/gallium/auxiliary/draw/draw_context.c

@@ -159,7 +159,7 @@ boolean draw_init(struct draw_context *draw)
 void draw_destroy( struct draw_context *draw )
 {
    struct pipe_context *pipe;
-   int i, j;
+   unsigned i, j;
 
    if (!draw)
       return;

src/gallium/auxiliary/draw/draw_gs.c

@@ -87,7 +87,7 @@ draw_create_geometry_shader(struct draw_context *draw,
                             const struct pipe_shader_state *state)
 {
    struct draw_geometry_shader *gs;
-   int i;
+   unsigned i;
 
    gs = CALLOC_STRUCT(draw_geometry_shader);
 
@@ -162,7 +162,7 @@ void draw_delete_geometry_shader(struct draw_context *draw,
 /*#define DEBUG_OUTPUTS 1*/
 static INLINE void
 draw_geometry_fetch_outputs(struct draw_geometry_shader *shader,
-                            int num_primitives,
+                            unsigned num_primitives,
                             float (**p_output)[4])
 {
    struct tgsi_exec_machine *machine = shader->machine;

src/gallium/auxiliary/draw/draw_pipe_stipple.c

@@ -73,7 +73,7 @@ screen_interp( struct draw_context *draw,
                const struct vertex_header *v1 )
 {
    uint attr;
-   int num_outputs = draw_current_shader_outputs(draw);
+   uint num_outputs = draw_current_shader_outputs(draw);
    for (attr = 0; attr < num_outputs; attr++) {
       const float *val0 = v0->data[attr];
       const float *val1 = v1->data[attr];

src/gallium/auxiliary/draw/draw_pt_vsplit_tmp.h

@@ -71,7 +71,7 @@ CONCAT(vsplit_primitive_, ELT_TYPE)(struct vsplit_frontend *vsplit,
    if (max_index - min_index > icount - 1)
       return FALSE;
 
-   if (elt_bias < 0 && min_index < -elt_bias)
+   if (elt_bias < 0 && (int) min_index < -elt_bias)
       return FALSE;
 
    /* why this check? */
@@ -158,19 +158,19 @@ CONCAT(vsplit_segment_cache_, ELT_TYPE)(struct vsplit_frontend *vsplit,
    }
    else {
       if (spoken) {
-         if (ib[ispoken] < -ibias)
+         if ((int) ib[ispoken] < -ibias)
             return;
          ADD_CACHE(vsplit, ib[ispoken] + ibias);
       }
 
       for (i = spoken; i < icount; i++) {
-         if (ib[istart + i] < -ibias)
+         if ((int) ib[istart + i] < -ibias)
             return;
          ADD_CACHE(vsplit, ib[istart + i] + ibias);
       }
 
       if (close) {
-         if (ib[iclose] < -ibias)
+         if ((int) ib[iclose] < -ibias)
             return;
          ADD_CACHE(vsplit, ib[iclose] + ibias);
       }