Add the EGL display as a context member.

Add the EGL display as a context member.

This prevents having to access the current display though TLS.

Change-Id: Ic93d0f88096a7e7e50318dbafb9b32da5fbc50a2
Reviewed-on: https://swiftshader-review.googlesource.com/5511
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Meng-Lin Wu <marleymoo@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>