PR: 3165
Submitted by: Daniel Richard G.
(cherry picked from commit 2df9ec01d563f9cc2deab07e8c3391059d476592)
(cherry picked from commit 0de70011adf6952e3b975d1a8a383879b64f3b77)
Submitted by: Bruce Stephens <bruce.stephens@isode.com>
Use same construct for EXHEADER in srp/Makefile as other makefiles to cope
with possibly empty EXHEADER.
This meant a slight renumbering in util/libeay.num due to symbols
appearing in 1.0.0-stable. However, since there's been no release on
this branch yet, it should be harmless.