recursive configure

Hi newlib, I hope you're well. Thanks for the great lib.

I'm porting newlib to BareMetal OS. I'm trying to understand the build
process. When I remove libgloss/Makefile.in, I can still configure
newlib - why? Shouldn't configure be recursive? I've tried configuring
libgloss separately but that fails.

Here's what I did in a script:

$ uname -sp
Linux x86_64
$ cat mail.sh
ver="4.4.0.20231231"
pkg=newlib-$ver
tar=$pkg.tar.gz

if [ ! -e $tar ]; then wget ftp://sourceware.org/pub/newlib/$tar; fi
tar xf $tar

rm -rf build; mkdir build; cd build
if ../$pkg/configure          >/dev/null; then echo configure works; fi
if ../$pkg/libgloss/configure >/dev/null; then echo configure libgloss works; fi
rm ../$pkg/libgloss/Makefile.in
if ../$pkg/configure          >/dev/null; then echo why does configure
still work?; fi

cd ..
$ bash mail.sh
configure works
configure: error: cannot run /bin/bash ../config.sub
why does configure still work?
$

thanks in advance,
jack