Unfortunately, $(AM_CPPFLAGS) gets overridden by per-target _CPPFLAGS
variables, which $(INCLUDES) did not, so this requires some additional
changes.
In most places, I have just gotten rid of the per-target _CPPFLAGS
variables; in directories with a single target, the per-target
variable is unnecessary, and in directories with multiple targets, the
per-target variable is often undesirable, since it forces some files
to be compiled twice, even though there ends up being no difference
between the two files.
Rather than generating enum classes by hand (and complaining in each
file that "this should really be standard"), use glib-mkenums.
Unfortunately, we need a very new version of glib-mkenums in order to
deal with NM's naming conventions and to fix a few other bugs, so just
import that into the source tree temporarily.
Also, to simplify the use of glib-mkenums, import Makefile.glib from
https://bugzilla.gnome.org/654395.
To avoid having to run glib-mkenums for every subdirectory of src/,
add a new "generated" directory, and put the generated enums files
there.
Finally, use Makefile.glib for marshallers too, and generate separate
ones for libnm-glib and NetworkManager.
