Fix print/texlive-base build for powerpc and powerpc64

print/texlive-base depends on devel/icu, which uses C++11 and links against
newer libstdc++ when built with gcc. All ports linking against some of the icu
libraries need to be built with a C++11 compiler, to link against the correct
libstdc++.

PR: 215770
Approved by: swills