There is an strange automake warning
Makefile.vapigen:49: warning: $(1) was already defined in condition TRUE, which includes condition ENABLE_VAPIGEN ...
Makefile.am:4: 'Makefile.vapigen' included from here
Makefile.glib:124: ... '$(1)' previously defined here
Makefile.am:1: 'Makefile.glib' included from here
when having
if ENABLE_VAPIGEN
include Makefile.vapigen
endif
That is worked around by removing the "if", which however
requires us to remove the error check in Makefile.vapigen.