fonts need cstdint

libraries/hershey_fonts/hershey_fonts.hpp

@@ -1,6 +1,7 @@
 #include <map>
 #include <string>
 #include <functional>
+#include <cstdint>
 
 namespace hershey {
   struct font_glyph_t {
@@ -50,4 +51,4 @@ namespace hershey {
 
   bool has_font(std::string_view font);
   const font_t* font(std::string_view font);
-}
+}