make sure non existent manpages don't get linked.

MORONIC cut&paste in Makefile. Some people really don't think.
Found out by fries and I, long story...

print/ghostscript/gnu/patches/patch-src_unixinst_mak

@@ -0,0 +1,12 @@
+$OpenBSD: patch-src_unixinst_mak,v 1.1 2003/08/11 23:11:29 espie Exp $
+--- src/unixinst.mak.orig	2003-08-12 01:00:31.000000000 +0200
++++ src/unixinst.mak	2003-08-12 01:00:47.000000000 +0200
+@@ -133,7 +133,7 @@ install-man: $(PSMANDIR)/gs.1
+ 			  ln -s ps2pdf.$(man1ext) $$f.$(man1ext) ) ;\
+ 	      done ;\
+ 	    fi ;\
+-	    if ( test -f $$man1dir/ps2ps.$(man1ext) ) ;\
++	    if ( test -f $$man1dir/gslp.$(man1ext) ) ;\
+ 	      then for f in $(MAN1_LINKS_GSLP) ;\
+ 	        do ( cd $$man1dir; rm -f $$f.$(man1ext) ;\
+ 			  ln -s gslp.$(man1ext) $$f.$(man1ext) ) ;\