Please give back asymptote on ppc64

[Hilmar Preuße]

Hello,

    We suspect there was a bug in gcc that caused asymptote binaries to
    crash (and FTBFS) on ppc64 architecture. We suspect This has been
    fixed in gcc 8.3.0-19. Please give back foo on ppc64.

      gb asymptote_2.49-2 . ppc64

    Thanks.