freetype pkconfig libpng interaction

Just want to check my understanding about this Makefile.freetype2 dependency...

> $(FREETYPE2LIB): pkgconfig libpng $(THIRDPARTYLIBDIR)/$(FREETYPE2LIBNAME)

> https://github.com/OpenSmalltalk/opensmalltalk-vm/blob/Cog/build.win32x86/third-party/Makefile.freetype2#L35

...that pkgconfig and libpng aren't required to build freetype independently?

(i.e. from a separate repo e.g. https://github.com/bencoman/freetype2)

They just plug in to freetype at runtime?

cheers -ben