[FIX] Set CMP0054 policy also within SeqAnBuildSystem.cmake for internal build.
[FIX] Set CMP0054 policy also within SeqAnBuildSystem.cmake for internal build.

xenigmax/seqan,xenigmax/seqan,xenigmax/seqan,xenigmax/seqan,xenigmax/seqan,xenigmax/seqan,xenigmax/seqan,xenigmax/seqan