Added dtype from const char pointer ctor

include/pybind11/numpy.h

@@ -125,6 +125,8 @@ public:
         m_ptr = from_args(pybind11::str(format)).release().ptr();
     }
 
+    dtype(const char *format) : dtype(std::string(format)) { }
+
     dtype(list names, list formats, list offsets, size_t itemsize) {
         dict args;
         args["names"] = names;