Raise default max-specpdl-size and max-lisp-eval-depth

Raise default max-specpdl-size and max-lisp-eval-depth

Recent changes have caused bootstrapping to fail for certain
configurations, and it was likely getting close to the limits
for others.  This change raises the limits to those previously
used when configured for nativecomp:

  max-specpdl-size raised from 1800 to 2500
  max-lisp-eval-depth raised from 800 to 1600

* src/eval.c (init_eval_once): Raise limits.
* doc/lispref/eval.texi (Eval):
* doc/lispref/variables.texi (Local Variables): Document new values.