MFH: r458012

lang/spidermonkey24: unbreak build with Clang 6 / GCC 7

js/src/shell/jsoptparse.cpp:256:22: error: comparison between pointer and integer ('char *' and 'int')

if (value[0] == '\0')
    ~~~~~~~~ ^  ~~~~

Reported by: antoine (via bug 224669)
Obtained from: upstream (SpiderMonkey 25.0)
Approved by: ports-secteam blanket