Upgrade tracker to 2.3.4 and tracker-miners to 2.3.5

Note that tracker was not upgraded to 2.3.6 due to build failures in both
2.3.5 and 2.3.6 with clang11 which I haven't been able to solved yet.

While here incorporate a patch to vala files which makes it compatible with both
vala 0.40 and vala 0.50

According to ABI laboratory (and my testings) this upgrade is backward compatible