build: rewrite libdw detection without pkg-config

build: rewrite libdw detection without pkg-config

pkg-config expected to be more convenient way to configure libdw,
but in practice it appeared to be less portable than good old
AC_CHECK_HEADERS and AC_CHECK_LIB.

* ci/install-dependencies.sh (common_packages): Remove pkg-config.
(STACKTRACE == "libdw"): Do not install libz-dev and liblzma-dev.
* debian/control (Build-Depends): Remove pkg-config.
* m4/st_libdw.m4 (st_ARG_LIBDW, st_LIBDW): Rewrite without pkg-config.