Strange failure building latest zsh w/Xcode on MacOS

[Bart Schaefer <schaefer@brasslantern.com>]

cd .. && /bin/sh $top_srcdir/Src/mkmakemod.sh Src Makemod
creating Src/Makemod.in
config.status: creating Src/Makemod
/bin/sh: line 0: cd: zsh.mdd: Not a directory
make[2]: *** [headers] Error 1
make[1]: *** [headers] Error 2

So I tried again after a "make clean" and that gives:

Src/../Src/mkmakemod.sh: line 93: Src/zsh.mdd/Makefile.in: Not a directory
make[3]: *** [prep] Error 1
make[2]: *** [../Src/modules.stamp] Error 2
make[2]: Target `headers' not remade because of errors.
make[1]: *** [headers] Error 2
rm -f stamp-modobjs.tmp
gcc -c -I. -I../Src -I../Src -I../Src/Zle -I.  -DHAVE_CONFIG_H -Wall
-Wmissing-prototypes -ggdb  -o main.o main.c
main.c:30:10: fatal error: 'zsh.mdh' file not found
#include "zsh.mdh"
         ^~~~~~~~~
1 error generated.
make[2]: *** [main.o] Error 1
make[1]: *** [main.o] Error 2
make[2]: *** No rule to make target `zsh.export'.
make[1]: *** [zsh.export] Error 2
make[1]: Target `all' not remade because of errors.
make: *** [all] Error 1

Tried "make realclean" and reconfigure, same problem.