[MacPorts] #54236: port:mesa & port:libepoxy : provide and support EGL

[MacPorts]

#54236: port:mesa & port:libepoxy : provide and support EGL
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  Reporter:  RJVB           |      Owner:
      Type:  enhancement    |     Status:  new
  Priority:  Normal         |  Milestone:
 Component:  ports          |    Version:
Resolution:                 |   Keywords:  haspatch
      Port:  mesa libepoxy  |
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Comment (by RJVB):

 I've attached an update for Mesa 17.1.6 which also adds `+llvmXY` variants
 allowing to build the gallium swrast driver.

 The main interest here is probably that this allows certain X11
 applications to render to remote displays despite the Xquartz lack of GLX
 support. For instance, after building Qt5 for xcb, applications that
 require shared OpenGL contexts or similar less common features will fail
 on startup with a "failed to initialise GLX" error. When using EGL instead
 they will run normally.

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Ticket URL: <https://trac.macports.org/ticket/54236#comment:2>
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