mesa: rework ParameterList to allow packing

Currently everything is padded to 4 components. Making the list
more flexible will allow us to do uniform packing.

V2 (suggestions from Nicolai):
- always pass existing calls to _mesa_add_parameter() true for padd_and_align
- fix bindless param value offsets
- remove left over wip logic from pad and align code
- zero out param value padding
- whitespace fix

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/mesa/program/prog_statevars.c

@@ -1076,9 +1076,10 @@ _mesa_load_state_parameters(struct gl_context *ctx,
 
    for (i = 0; i < paramList->NumParameters; i++) {
       if (paramList->Parameters[i].Type == PROGRAM_STATE_VAR) {
+         unsigned pvo = paramList->ParameterValueOffset[i];
          _mesa_fetch_state(ctx,
 			   paramList->Parameters[i].StateIndexes,
-                           &paramList->ParameterValues[i][0]);
+                           paramList->ParameterValues + pvo);
       }
    }
 }