Unix Makefile: Some sed implementation truncate long lines. Use perl instead.

Fixes #1781
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1813)

Configurations/unix-Makefile.tmpl

@@ -302,7 +302,7 @@ distclean: clean
 depend:
 	@: {- output_off() if $disabled{makedepend}; "" -}
 	@if egrep "^# DO NOT DELETE THIS LINE" Makefile >/dev/null && [ -z "`find $(DEPS) -newer Makefile 2>/dev/null; exit 0`" ]; then :; else \
-	  ( sed -e '/^# DO NOT DELETE THIS LINE.*/,$$d' < Makefile; \
+	  ( $(PERL) -pe 'exit 0 if /^# DO NOT DELETE THIS LINE.*/' < Makefile; \
 	    echo '# DO NOT DELETE THIS LINE -- make depend depends on it.'; \
 	    echo; \
 	    for f in $(DEPS); do \