[11] avoid -std=c++11 CXX harfbuzz buildflag on Windows

The Visual Studio compilers (checked VS2013 and VS2017) do not know this flag, output is
cl : Command line warning D9002 : ignoring unknown option '-std=c+11'

So the flag should be avoided on Windows.

JDK 17 and above use c++14 already, that's why this change is for 11u only.