mesa-libs: Add glesv1 lib

[manu]

Summary

There is no real reason to disable glesv1 so add it to the build.
While here add a USE_GL for it.

[zeising]

Can you double check that graphics/libepoxy doesn't need updating as well. Just build it in poudriere with this change to mesa and see if it works.
Looking good otherwise.

[zeising]

Also, portmgr is blocking review because changes to Mk/, but Mk/Uses/gl.mk is x11@ responsibility, so it should be OK.

[manu]

libepoxy is ok.
Why did you though there could be a problem ?

[zeising]

Libepoxy is some glue library, and it had an explicit dep on glesv2, so I thought it might do things with glesv1 as well. I just wanted to be sure.