intel: Improve INTEL_DEBUG=fbo output.

src/mesa/drivers/dri/intel/intel_fbo.c

@@ -427,7 +427,8 @@ intel_update_wrapper(GLcontext *ctx, struct intel_renderbuffer *irb,
       DBG("Render to DEPTH_STENCIL texture OK\n");
    }
    else {
-      DBG("Render to texture BAD FORMAT %d\n", texImage->TexFormat);
+      DBG("Render to texture BAD FORMAT %s\n",
+	  _mesa_get_format_name(texImage->TexFormat));
       return GL_FALSE;
    }
 
@@ -594,6 +595,9 @@ intel_validate_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb)
       /* we only support combined depth/stencil buffers, not separate
        * stencil buffers.
        */
+      DBG("Only supports combined depth/stencil (found %s, %s)\n",
+	  depthRb ? _mesa_get_format_name(depthRb->Base.Format): "NULL",
+	  stencilRb ? _mesa_get_format_name(stencilRb->Base.Format): "NULL");
       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
    }
 
@@ -605,6 +609,7 @@ intel_validate_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb)
 	 continue;
 
       if (irb == NULL) {
+	 DBG("software rendering renderbuffer\n");
 	 fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 	 continue;
       }