contrib/buildsystems: fix misleading error message

The error message talked about a "lib option", but it clearly referred
to a link option.

Signed-off-by: Philip Oakley <philipoakley@iee.org>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

contrib/buildsystems/engine.pl

@@ -333,7 +333,7 @@ sub handleLinkLine
         } elsif ($part =~ /\.obj$/) {
             # do nothing, 'make' should not be producing .obj, only .o files
         } else {
-            die "Unhandled lib option @ line $lineno: $part";
+            die "Unhandled link option @ line $lineno: $part";
         }
     }
 #    print "AppOut: '$appout'\nLFlags: @lflags\nLibs  : @libs\nOfiles: @objfiles\n";