Make building the debian packages work again. I've verified that it
works in my own OBS namespace.
This patch also adds missing pkgconf variables in host/Makefile.am, so
libosmo-simtrace2.pc installs properly.
Related: OS#4283
Fixes: 964cda309d ("host: use autotools and split shared code to libosmo-simtrace2")
Change-Id: I2377de1e8b149520922217a1ab16f6e22fe6462a