[Bf-cycles] Build without OpenImageIO

[Guillaume Chéreau]

It is actually not difficult to replace oiio ustring with std::string
in the code, since the api are almost the same, but the performance
are probably not as good with std::string.

In util/util_param.h, I can comment out the OpenImageIO/ustring.h
include and add those lines:

// ustring implementation based on std::string.
class ustring : public std::string
{
public:
    ustring() {}
    explicit ustring(const char *str) : std::string(str) {}
    ustring (const ustring &str) : ustring(str.c_str()) {}
    ustring (const std::string &str) : ustring(str.c_str()) {}
    const std::string &string() const { return *this; }
    operator int(void) const { return !empty(); }
    const ustring &operator=(const char *str) { *this = str; return *this; }
};
typedef std::hash<std::string> ustringHash;

And the compilation works.

Similar treatment can be done for typedesc.


Regards,
Guillaume

-- 
Guillaume
guillaume.chereau at gmail.com
+886 970422910