glsl: re-validate program pipeline after sampler change

Cc: "11.1" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Cc: Kenneth Graunke <kenneth@whitecape.org>
https://bugs.freedesktop.org/show_bug.cgi?id=93180

src/mesa/main/uniform_query.cpp

@@ -758,6 +758,10 @@ _mesa_uniform(struct gl_context *ctx, struct gl_shader_program *shProg,
             return;
          }
       }
+      /* We need to reset the validate flag on changes to samplers in case
+       * two different sampler types are set to the same texture unit.
+       */
+      ctx->_Shader->Validated = GL_FALSE;
    }
 
    if (uni->type->is_image()) {