Although having different parts of NM in different subdirectories
keeps the source tree neat, it has made the build messy, particularly
because of cross-dependencies between the subdirs.
Reorganize to build all of the pieces of the NetworkManager binary
from src/Makefile, and only use recursive make for test programs,
helper binaries, and plugins.
As part of this, get rid of all the per-directory convenience
libraries, and switch to building a single top-level
libNetworkManager.la, containing everything except main.c, which all
of the test programs can then link against.
This functionality is (mostly) obsoleted by the newer
GLIB_VERSION_MIN_REQUIRED and GLIB_VERSION_MAX_ALLOWED defines. With
this, your build doesn't all of a sudden blow up if we deprecate
something in GLib - you have to explicitly opt-in to the newer
version.
G_DISABLE_DEPRECATED does still apply for macros and things that can't
take __attribute__((deprecated)), but it's not really worth the pain
and cargo culting around just for that.
Commit 217c5bf6ac fixed processing of unix
signals: signals are blocked in all threads and a dedicated thread handles the
signals using sigwait().
However, the commit forgot that child processes inherit signal mask as well.
That is why we have to unblock signals for child processes we spawn from NM, so
that they can receive signals.
