>=mate-system-monitor-1.13.0 dropped GTK+2 support

[SmoothDude]

And due this build with GTK+2 support fails. Here are 3 options:

• Follow this change and remove GTK+2 support from ebuild as well
• Adopt new changes from 1.13.0 in a form of patch to GTK+2 version
• Temporary remove mate-system-monitor-1.13.0

[rinaldus]

I removed GTK 2 support and made GTK 3 support as default. It works in my computer now. Please, check.