You need FontForge to build the fonts, on Debian known as "fontforge" package.
http://fontforge.github.io/en-US/
Also pearl module Font::TTF, Debian package "libfont-ttf-perl".
https://metacpan.org/release/Font-TTF/
Tool "make" to make, Debian package "make".



$ make full-ttf

will all fonts to TrueType format with all glyphs included



$ make  lgc-ttf

will build the fonts with only the LGC (Latin-Greek-Cyrillic) subset



If you just do

$ make

you will also make new status files. In that case you need to have the following files

- Get the current Unicode files and copy them into the "resources" folder
wget http://www.unicode.org/Public/UNIDATA/UnicodeData.txt
wget http://www.unicode.org/Public/UNIDATA/Blocks.txt

- Get the current fc-lang orthographies from the fontconfig repository:
git clone git://anongit.freedesktop.org/git/fontconfig ~/repos/fontconfig

- Create a symlink to the appropriate folder:
ln -s ~/repos/fontconfig/fc-lang resources/fc-lang