x11/xforward: Fix build with LLVM15 and other fixes

In addition to fixing the build with LLVM15, a number of packages xforward
depends on no longer provide static libraries, making building the static
version impossible. Therefore this revision also reverts f6d424b24071
(SVN r414578 in May 2016) which added a static build option.

(cherry picked from commit 91bb18500a34e6ffa1eee79c386711ac32679ae5)