Comment # 4 on bug 1208670 from Yasuhiko Kamata

> I think, the dependency on "atk" can be eliminated?

Yes, you are right.
About to Tumbleweed, "atk-devel" was replaced by "at-spi2-core-devel".
Both of them can be specified as "pkgconfig(atk)", so updated spec like that
and re-enabled.

In addition, there are some unnecessary (not used) definitions as follows:
* gb.qt/src/ext/CEditor.h: "marginClicked()"
* gb.image/src/qt.h: "myQColor"

These definitions caused unnecessary build failure in Leap 15.5 and Tumbleweed.
So added "gambas2-remove-unused-symbols.patch".