Use lcov for both Fedora and MSYS2 to create coverage reports and add a second
ci stage which merges the coverage and creates a html report using genhtml.
In the final stage, which is only run on master, the result is published on
gitlab pages.
https://bugzilla.gnome.org/show_bug.cgi?id=795636
Fix various warnings regarding unused variables, duplicated
branches etc by adjusting the ifdeffery and some missing casts.
gnulib triggers -Wduplicated-branches in one of the copied files,
disable as that just makes updating the code harder.
The warning indicating missing features are made none fatal through
pragmas. They still show but don't abort the build.
https://bugzilla.gnome.org/show_bug.cgi?id=793729
This builds glib using meson/ninja/ccache with mingw-w64 on a Windows
machine.
The CI scripts expect a gitlab runner to exist with the "win32" tag
which uses the default "cmd" shell by default.
Before running the tests pacman is invoked to update the system
(potentially including bash etc, thus the extra step)
Then a login shell is started with CHERE_INVOKING to not change the
cwd and finally the test script is executed.
https://bugzilla.gnome.org/show_bug.cgi?id=793729
