Replace gl_frag_attrib enum with gl_varying_slot.

This patch makes the following search-and-replace changes:

gl_frag_attrib -> gl_varying_slot
FRAG_ATTRIB_* -> VARYING_SLOT_*
FRAG_BIT_* -> VARYING_BIT_*

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Tested-by: Brian Paul <brianp@vmware.com>
diff --git a/src/mesa/main/ffvertex_prog.c b/src/mesa/main/ffvertex_prog.c
index 3f08b09..093bc66 100644
--- a/src/mesa/main/ffvertex_prog.c
+++ b/src/mesa/main/ffvertex_prog.c
@@ -165,7 +165,7 @@
 
    if (ctx->RenderMode == GL_FEEDBACK) {
       /* make sure the vertprog emits color and tex0 */
-      key->fragprog_inputs_read |= (FRAG_BIT_COL0 | FRAG_BIT_TEX0);
+      key->fragprog_inputs_read |= (VARYING_BIT_COL0 | VARYING_BIT_TEX0);
    }
 
    key->separate_specular = (ctx->Light.Model.ColorControl ==
@@ -1407,7 +1407,7 @@
 
    for (i = 0; i < MAX_TEXTURE_COORD_UNITS; i++) {
 
-      if (!(p->state->fragprog_inputs_read & FRAG_BIT_TEX(i)))
+      if (!(p->state->fragprog_inputs_read & VARYING_BIT_TEX(i)))
 	 continue;
 
       if (p->state->unit[i].coord_replace)
@@ -1575,22 +1575,22 @@
 
    /* Lighting calculations:
     */
-   if (p->state->fragprog_inputs_read & (FRAG_BIT_COL0|FRAG_BIT_COL1)) {
+   if (p->state->fragprog_inputs_read & (VARYING_BIT_COL0|VARYING_BIT_COL1)) {
       if (p->state->light_global_enabled)
 	 build_lighting(p);
       else {
-	 if (p->state->fragprog_inputs_read & FRAG_BIT_COL0)
+	 if (p->state->fragprog_inputs_read & VARYING_BIT_COL0)
 	    emit_passthrough(p, VERT_ATTRIB_COLOR0, VARYING_SLOT_COL0);
 
-	 if (p->state->fragprog_inputs_read & FRAG_BIT_COL1)
+	 if (p->state->fragprog_inputs_read & VARYING_BIT_COL1)
 	    emit_passthrough(p, VERT_ATTRIB_COLOR1, VARYING_SLOT_COL1);
       }
    }
 
-   if (p->state->fragprog_inputs_read & FRAG_BIT_FOGC)
+   if (p->state->fragprog_inputs_read & VARYING_BIT_FOGC)
       build_fog(p);
 
-   if (p->state->fragprog_inputs_read & FRAG_BITS_TEX_ANY)
+   if (p->state->fragprog_inputs_read & VARYING_BITS_TEX_ANY)
       build_texture_transform(p);
 
    if (p->state->point_attenuated)