Update BUILD.md
Update BUILD.md

Added cmake "build release" configurations to Raspberry Pi build instructions: -DCMAKE_BUILD_TYPE="Release"
csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,csound/csound,csound/csound,csound/csound,ketchupok/csound,ketchupok/csound,csound/csound,csound/csound,csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,ketchupok/csound,csound/csound,ketchupok/csound,ketchupok/csound,ketchupok/csound