www/webkit-qt4: unbreak with clang 4.0

html/HTMLImageElement.cpp:77:24: error: ordered comparison between pointer and zero ('const int *' and 'int')

if (optionalHeight > 0)
    ~~~~~~~~~~~~~~ ^ ~

PR: 216015
Regressed by: https://github.com/llvm-mirror/clang/commit/4b6ad14285f3
Obtained from: upstream (excerpt)
Approved by: portmgr blanket