app-misc/tracker: workaround compilation issue against vala:0.44

app-misc/tracker: workaround compilation issue against vala:0.44

Limit to vala-0.42 and older for now. With >=vala-0.44.5:0.44 it is
crashing g-ir-compiler somehow, while it is fine with older vala,
including 0.44.4. It seems to also be fine with p.masked vala-0.45.3.
Needs more investigation, as it may be affecting other packages as
well if it's a vala:0.44 regression, not a tracker problem, but
meanwhile this workaround gets things going for ~arch users again.

Bug: https://bugs.gentoo.org/691072
Package-Manager: Portage-2.3.62, Repoman-2.3.12
Signed-off-by: Mart Raudsepp <leio@gentoo.org>