The build of `pangomm` 2.42 is broken due to a missing include statement
in `attrlist.cc` (a generated source file).
Others have already run into this issue and @dslm4515 has outlined a
patch in a respective issue on their BMLFS project [1].
[1]: https://github.com/dslm4515/BMLFS/issues/16#issuecomment-914624797
