Obsolescence note: the builder image has been updated since this was written. A newer snapshot can be found at Windows builder snapshot 1809.
Oh, you mean mingw. It’s not quite “Windows”.
I’ve got a snapshot of the Windows Builder directory structure and environment (as seen from Git Bash) with the following test .yml:
os: windows
language: shell
script:
- find /c | gzip >disk.txt.gz
- set >env.txt
- curl -T "{disk.txt.gz,env.txt}" ftp://<user>:<passwd>@<your_ftp_server>/
It shows that there’s no mingw-get or pacman but there’s /c/ProgramData/chocolatey/lib/mingw/tools/install/mingw64/opt/include/ncursesw/ncurses.h.
So you should probably be able to #include <ncurses.h>, likely with adding a -I.