The aim of this package is to make reading the INSTALL file unnecessary. So
next time try running:

$ bpkg build libxerces-c

But if you don't want to use the package manager, then you can also build this
package manually using the standard build2 build system.

Note that by default libxerces-c is built without network support. To enable
it, run the following command instead:

$ bpkg build libxerces-c +{ config.libxerces_c.network=true }