* Makefile.tpl (all.normal): Rename to all.
(all): Replace with a rule to pick the default
target from configure.
(all-gcc, configure-gcc): Use conditionals to
do nothing when toplevel bootstrap is going on.
(GCC directory bootstrap) [gcc-bootstrap]: Disable.
(Toplevel bootstrap) [gcc-no-bootstrap]: Disable.
* configure.in: Support --enable-bootstrap.