The glib-genmarshal tool was rewritten in GLib 2.53.3, and now supports
more command line arguments, such as:
"--pragma-once": emits a "#pragma once" instead of the old header
guards when generating the header file
"--prototypes": emits the marshallers prototype when generating the
source file
"-D,-U": defines and undefines pre-processor symbols
"--include-header": emits an "#include" directive when generating the
source file for the specified header file
Meson should take advantage of these new options, as they can be used to
replace most of the ad hoc build rules that projects are currently using
to implement the same thing.
Instead of mapping each option to a named argument, I used the same
approach as the compile_resources() and generate_gir() methods; the
genmarshal() method now has an 'extra_args' argument that can be used to
pass extra arguments to the glib-genmarshal tool.