st/mesa: Fix memory leak in out-of-memory path.

Fixes Coverity resource leak defect.

Signed-off-by: Vinson Lee <vlee@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/state_tracker/st_atom_pixeltransfer.c

@@ -266,6 +266,7 @@ get_pixel_transfer_program(struct gl_context *ctx, const struct state_key *key)
    if (!fp->Base.Instructions) {
       _mesa_error(ctx, GL_OUT_OF_MEMORY,
                   "generating pixel transfer program");
+      _mesa_free_parameter_list(params);
       return NULL;
    }