[tlbuild] asy2.48

[Karl Berry]

John (Bowman) has released asy 2.48. It is in the usual TL directory
now, Build/source/utils/asymptote. Please give it a try and send me
binaries. I will wait until at least tomorrow to install the support
files, to have a chance of binaries on at least the major platforms.

Nothing else of note in the source tree has changed -- just looking for
asy (if provided in the past).

Regarding Macs, John warns:

  I haven't tested this release under MacOSX; there may well be problems
  with the GLEW library location (or even the existence of this library)
  on that platform; so feedback and patches would be most
  welcome. Apparently Apple has begun phasing out OpenGL support
  (although they say it will still be supported for a while longer).

For myself, I was unable to compile it on tug (centos7), since, I guess,
I don't have enough of OpenGL installed at the moment. (<glm/glm/hpp>
not found.) Norbert, can you try please?

Thanks,
Karl