I am trying to install a ruby gem, but the installation process is stopped, because:
ld: file not found: /usr/local/lib/libfreetype.6.dylib for architecture x86_
Your compiler is trying to link to an lib at a location that doesn't have the lib, however it seems that you have installed it with homebrew.
Try running
ln -s /usr/local/Cellar/freetype/2.4.10/lib/libfreetype.6.dylib /usr/local/lib/libfreetype.6.dylib
to create one, or you can just use the without-freetype
flag to skip it.