This is a new rules section that allows defining rules to modify
component definitions. This is useful to add repetitive dependencies,
for example, as in the case of "type = script/lua" that always requires
the "support.lua-scripting" feature. This can also be useful to modify
other component properties, such as the arguments, in overriding
configuration files, without needing to redefine the whole components
section.
A profile is a list of features set to required/optional/disabled
which governs which components are getting loaded, given a static
components list with well-defined dependencies
Each component can now list required and optional dependencies,
using the component feature names to match other components.
In addition, each component feature can be declared as required, optional
or disabled, making optional components easier to deal with.
The component flags (ifexists, nofail) have been removed.
Using virtual components, this system also allows easier customization
of which components should be loaded for a specific configuration,
without requiring the user to copy the list of components and edit it.
Also bump the required glib version to 2.68 for g_assert_cmpstrv()
