Import flex-2.5.37 to new vendor branch
Merge branch 'vendor/FLEX'
flex: Add local modifications and DragonFly READMEs

The quality of the latest flex 2.5.37 release is pretty poor.  The
man page displayed the wrong version, the code doesn't compile with
GCC 4.7, the new lerrs_fatal function missing a protocol and then
given the wrong type once when it was called.  Some of the errors
could have been fixed with higher WARNS settings but these patches
applied over the flex vendor branch should fix the bugs.

The standard DragonFly README files are added at the same time.
flex: Add world makefiles, but don't tie it into build yet.
flex/lex: Activate flex 2.5.37, deactivate lex 2.5.4

Flex is a bootstrap tool.  This swaps the new flex for the old lex.
The old lex subdirectory should stay in place for around a week in case
we need to revert this change for any reason.
kernel: Fix the build of the SOEKRIS kernel config.

It's the only one that has if_ath and 80211 in the kernel and ATH_DEBUG
and IEEE80211_DEBUG isn't set at the same time. So it caught a few
ethstr[] that were not yet under the proper #ifdef.