do not use boost::format and streams in osv::printf() and osv::debug()

[wkozaczuk]

• reimplement some usage of osv::sprintf() by using std::to_string() instead

• eliminate osv::fprintf*()functions and replace most of their usages with new osv::sprintf()

• eliminate usage of std::ostringstream and std::stringstream in some cases by simple concatenation of std::string

• replace template-based std::string sprintf(const char* fmt, args... as) with new std::string sprintf(const char* fmt...)

• add std::string vsprintf(const char* fmt, va_list ap)

• replace void debug(const char* fmt, args... as) and its usages with new void debugf(const char* fmt...) that delegates to osv::vsprintf()

• rename the C version of void debugf(const char *fmt, ...) to void debugff(const char *fmt, ...) to avoid name collision and adjust references in the code

• add any missing headers

This is another commit to remove code that directly or indirectly depends on std::locale.

Ref #1335