PolyBoRi fails to build on cygwin

[mhansen]

It fails with

  /home/mhansen/sage-4.2/spkg/build/gd-2.0.35.p2/src/gd_png.c:70: undefined reference to `_png_get_error_ptr'
  /home/mhansen/sage-4.2/local/lib/libgd.a(gd_png.o): In function `gdPngReadData':
  /home/mhansen/sage-4.2/spkg/build/gd-2.0.35.p2/src/gd_png.c:85: undefined reference to `_png_get_io_ptr'
  /home/mhansen/sage-4.2/spkg/build/gd-2.0.35.p2/src/gd_png.c:87: undefined reference to `_png_error'
  /home/mhansen/sage-4.2/local/lib/libgd.a(gd_png.o): In function `gdPngWriteData':
  /home/mhansen/sage-4.2/spkg/build/gd-2.0.35.p2/src/gd_png.c:94: undefined reference to `_png_get_io_ptr'
  /home/mhansen/sage-4.2/local/lib/libgd.a(gd_png.o): In function `gdImageCreateFromPngCtx':
  /home/mhansen/sage-4.2/spkg/build/gd-2.0.35.p2/src/gd_png.c:152: undefined reference to `_png_check_sig'

This can be fixed by adding png12 and z to the list of libraries needed when gd is present.

I'll post an spkg shortly.

[mhansen]

This no longer fails with Cygwin 1.7.

[mhansen]

So, it turns out this is still an issue.

[mhansen]

There's an spkg which should fix this at ​http://sage.math.washington.edu/home/mhansen/polybori-0.6.4.p1.spkg

[was]

looks good