nir: put compact into bitfields in nir_variable_data

This being declared bool means it won't get merged with the previous
bitfields, this seems like an oversight rather than deliberate.

Noticed when running pahole.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/compiler/nir/nir.h

@@ -220,7 +220,7 @@ typedef struct nir_variable {
        * be tightly packed.  In other words, consecutive array elements
        * should be stored one component apart, rather than one slot apart.
        */
-      bool compact:1;
+      unsigned compact:1;
 
       /**
        * Whether this is a fragment shader output implicitly initialized with