Build libtermcap*.so instead of (or in addition to) libtermcap.a

[was]

Some components of Sage, e.g., libsingular, link in the systemwide libtermcap.so dynamically instead of statically linking the libtermcap.a that is built by the Sage termcap spkg. This is a *big problem* when building a binary on a system that has libtermcap.so and trying to run it on another system that does not have that so.

Solution?: Modifying the spkg-install script for termcap so it also builds the so libraries.

• See also #12725, which changes the termcap spkg...

[jdemeyer]

The version of termcap in Sage (i.e. the official upstream version) does not support building shared libraries. So, I am a bit surprised to see the file libtermcap.so appear on your system. Could you try whether the spkg from #12725 fixes the problem? i.e. build termcap from #12725 and then rebuild Singular and check whether local/lib/libsingular.so still links against libtermcap.so

[was]

As described this can't be fixed, so "wontfix".