PR 232997

• Unbreak build by adding "-ftemplate-depth=1024" to CXXFLAGS
• Add missing libraries

While I'm here:

• Fix license and add path to license file
• Add "gnome" to USES because using USE_GNOME alone is deprecated
• Pet portlint

• poudriere (11.2-, 12.0-RELEASE, 13.0-CURRENT@r342772 amd64 + i386) -> OK
• portlint -> OK (just warns about the BUILD_DEPENDS=${RUN_DEPENDS} [...] construct)
• Runtime tests -> OK

It builds also fine on the 2019Q1 branch for the case if a MFH is required/accepted.