during "make errors" and thus during "make update".

Fix lots of bugs that util/ck_errf.pl can detect automatically.
Various others of these are still left to fix; that's why
"make update" will complain loudly when run now.

("perl util/ck_errf.pl */*.c */*/*.c" still reports many more.)

move some functions from exported header <openssl/dtl1.h> into "ssl_locl.h";
fix silly indentation (a TAB is *not* always 4 spaces)