Makefile.def (STAGE2_CFLAGS, [...]): Add to flags_to_pass.

Makefile.def (STAGE2_CFLAGS, [...]): Add to flags_to_pass.

ChangeLog:
* Makefile.def (STAGE2_CFLAGS, STAGE3_CFLAGS, STAGE4_CFLAGS):
Add to flags_to_pass.  Adjust uses of BOOT_CFLAGS.
(bootstrap2-debug, bootstrap-debug): New bootstrap stages.
* Makefile.tpl (STAGE2_CFLAGS, STAGE3_CFLAGS, STAGE4_CFLAGS): New.
(do-compare, do-compare3, do-compare-debug): New.
([+compare-target+]): Use them.
contrib/ChangeLog:
* compare-debug: New.

From-SVN: r127570