gen-casefold-txt.pl and gen-casemap-txt.pl are licensed under GPLv2+, so
they are not touched by this commit.
A lot of *.c files in tests/ don't have a license header.
https://bugzilla.gnome.org/show_bug.cgi?id=776504
"make check" was failing on sys/resource.h not being available on
win32. Seeing that this test just spews some numbers on stdout
whithout really testing anything we can safely replace them with
similar enough numbers by relying on g_get_monotonic_time ().
Fixes https://bugzilla.gnome.org/show_bug.cgi?id=682386