Install Opengl in Savio using Spack

While installing Opengl, I met problems with the following error message.

I have written opengl in spack packages by using vim $HOME/.spack/linux/packages.yaml and do not know why it does not work.

But perl has been installed.

Could you tell me what is the problem and how to get Opengl installed? Thanks a lot!

Have you manually install mesa?

I have installed mesa before. But I am not sure whether I installed mesa successfully. When I type locate mesa, it will show

I asked Zhenxiang, and he said though he successfully installed mesa, it will get the result showing no mesa by using which mesa command.
What command should I use to check whether mesa is successfully installed?

Can you list the files under the ~/mesa folder in your home directory. Do ls ~/mesa to list files