only include <unicode/unistr.h> if ICU >= 59 (attempting to fix current `coverage` build on travis).
only include <unicode/unistr.h> if ICU >= 59 (attempting to fix current `coverage` build on travis).

mapycz/mapnik,mapycz/mapnik,mapycz/mapnik,CartoDB/mapnik,CartoDB/mapnik,CartoDB/mapnik