Please try again, I added a fix that should remove %DUMBFW if it's not
I couldn't test the fix on my local machine because I cannot recreate the problem there.
gnutls.o: In function `Fgnutls_available_p':
gnutls.c:(.text+0x105d): undefined reference to `gnutls_ext_get_name'
collect2: error: ld returned 1 exit status
make: *** [temacs] Error 1
make: Leaving directory `/tmp/emacs-emacs-26/src'
make: *** [src] Error 2
make: Leaving directory `/tmp/emacs-emacs-26'