Fix build with clang-4.0. Error log:

/wrkdirs/usr/ports/graphics/iccexamin/work/icc_examin-0.55/icc_profile_tags.cpp:352:28: error: ordered comparison between pointer and zero ('char *' and 'int')

while (strchr(txt, 13) > 0) { // \r 013 0x0d
       ~~~~~~~~~~~~~~~ ^ ~

/wrkdirs/usr/ports/graphics/iccexamin/work/icc_examin-0.55/icc_profile_tags.cpp:357:15: error: ordered comparison between pointer and zero ('char *' and 'int')

if (pos > 0) {
    ~~~ ^ ~

Reported by: FreeBSD package builder