thanks for the tip bluebrother, I reinstalled Cygwin in DOS text mode and tried "mount -f -t -s c:\\cygwin\\lib /usr/lib". This does not work. I'm thinking it's a repository problem as the folder gets configured correctly with no errors.
Here's a fresh build after putting it into DOS text & running the command:
$ make
make[1]: `rdf2binary' is up to date.
make[1]: `convbdf' is up to date.
make[1]: `codepages' is up to date.
make[1]: `scramble' is up to date.
make[1]: `bmp2rb' is up to date.
MAKE in bitmaps/mono
AR+RANLIB libbitmapsmono.a
MAKE in bitmaps/native
BMP2RB rockboxlogo.320x98x16.bmp
CC rockboxlogo.320x98x16.c
BMP2RB usblogo.176x48x16.bmp
CC usblogo.176x48x16.c
BMP2RB default_icons.6x8x16.bmp
CC default_icons.6x8x16.c
AR+RANLIB libbitmapsnative.a
MAKE in bitmaps/mono
make[2]: Nothing to be done for `all'.
MAKE in bitmaps/native
make[2]: Nothing to be done for `all'.
GENLANG afrikaans.lang
make[1]: *** [/rockbox/build/apps/lang/afrikaans.lng] Error 53
make: *** [langs] Error 2
note: /rockbox/build/apps/lang/afrikaans.lng does not exist. It's in /rockbox/apps/lang/afrikaans.lang, But it's spelt differently and is not my language. I can't find where GENLANG is set, which I suspect is why It's not compiling
EDIT: make[1]: *** No rule to make target `/rockbox/build/apps/lang/afrikaans.lng', needed by `/rockbox/build/max_language_size.h'.
That's what is reported when I delete afrikaans.lng file.