+TK/02 Rewrote SPF support to work with libspf2 versions >1.2.0.
+
+TK/03 Merged latest SRS patch from Miles Wilton.
+
+PH/05 There's a shambles in IRIX6 - it defines EX_OK in unistd.h which conflicts
+ with the definition in sysexits.h (which is #included earlier).
+ Fortunately, Exim does not actually use EX_OK. The code used to try to
+ preserve the sysexits.h value, by assumimg that macro definitions were
+ scanned for macro replacements. I have been disabused of this notion,
+ so now the code just undefines EX_OK before #including unistd.h.
+