XawListChange 2nd parameter may or may not be const

[jamesjer]

Fedora Rawhide recently updated to libXaw 1.0.16 and now we have an incompatible pointer type issue yet again. The prototype for XawListChange has 5 parameters, 4 of which are the same across libXaw versions. The second parameter, list, has different types:

• In libXaw 1.0.13 and earlier, it has type char **
• In libXaw 1.0.14 and 1.0.15, it has type _Xconst char **
• in libXaw 1.0.16, it has type String *, where String is a typedef for char *, so equivalent to char **

The libXaw 1.0.16 release notes say that a lot of client software was broken by the addition of const in version 1.0.14, so that change was reverted. I want to build xgap for Fedora 38, 39, 40, and Rawhide. We have libXaw 1.0.14 in Fedora 38 and 39, 1.0.15 in Fedora 40, and 1.0.16 in Rawhide.

To make things more fun, libXaw upstream has not provided any simple way of telling which prototype is going to be in scope. There is a preprocessor constant XawVersion, but its value is 7000002L in every release from 1.0.13 on. A version number that never changes does not seem very useful. Anyway, I guess some configure magic will be necessary to choose the right type for that second parameter.

[jengelh]

#33