nir/spirv: Allow pointless variable decorations on inputs

SPIR-V specifies that a bunch of stuff gets applied to types.  This means
taht a local variable could get, for instance, an array stride.  Just
because it's pointless doesn't mean you'll never see it.

src/compiler/spirv/vtn_variables.c

@@ -1050,6 +1050,8 @@ var_decoration_cb(struct vtn_builder *b, struct vtn_value *val, int member,
    case SpvDecorationArrayStride:
    case SpvDecorationGLSLShared:
    case SpvDecorationGLSLPacked:
+      break; /* These can apply to a type but we don't care about them */
+
    case SpvDecorationBinding:
    case SpvDecorationDescriptorSet:
    case SpvDecorationNoContraction: