conda-forge release of simuPOP 1.1.12 fails

[BoPeng]

https://github.com/conda-forge/simupop-feedstock/pull/29

The conda package for simuPOP 1.1.12 failed to build because the test fails on some platforms.

 Testing tr1 support: no
  Testing c++ library: libc++
  Building static libraries
  Failed to build a shared supporting library: command 'cc' failed: No such file or directory

under windows, there is something like ssize_t is not defined.

I hope someone could invest a little bit of time and check what is going on.

[BoPeng]

The new release also fails with error message like cc not found. Should be an easy fix.

https://github.com/conda-forge/simupop-feedstock/pull/32#issuecomment-2027772151