I did a clean pull from 'master' ( commit id:
b87c874aa1016939ccbee4cd3bd1384726cb2220 ), followed by './configure
--with-x-toolkit=gtk3 --with-xwidgets --with-modules; make' and I get:

make -C ../lisp compile-first EMACS="../src/bootstrap-emacs"
make[2]: Entering directory '/home/deech/emacs/lisp'
make[2]: Nothing to be done for 'compile-first'.
make[2]: Leaving directory '/home/deech/emacs/lisp'
make[2]: Entering directory '/home/deech/emacs/lisp'
  ELC      ../lisp/files.elc
Directory-local variables error: (invalid-read-syntax #)

In toplevel form:
files.el:31:1:Error: Symbol’s value as variable is void: =
make[2]: *** [Makefile:285: ../lisp/files.elc] Error 1
make[2]: Leaving directory '/home/deech/emacs/lisp'
make[1]: *** [Makefile:736: ../lisp/files.elc] Error 2
make[1]: Leaving directory '/home/deech/emacs/src'
make: *** [Makefile:421: src] Error 2

Thanks!
-deech