Use wcstombs when iconv is not present (#223)

Replace the jerry-built UTF-16 => Latin-1 code path with a cross-platform wcstombs solution that emits UTF-8.

This adds an element to the end of the MdbHandle struct, but should not break any existing code.

A run-time option could be added later to emit other encodings, but people who care about such things can just use the iconv code path.

include/mdbtools.h

@@ -39,6 +39,11 @@
 
 #ifdef HAVE_ICONV
 #include <iconv.h>
+#else
+#ifdef HAVE_XLOCALE_H
+#include <xlocale.h>
+#endif
+#include <locale.h>
 #endif
 
 #ifdef _WIN32
@@ -291,6 +296,10 @@ typedef struct {
 #ifdef HAVE_ICONV
 	iconv_t	iconv_in;
 	iconv_t	iconv_out;
+#elif defined(_WIN32) || defined(WIN32) || defined(_WIN64) || defined(WIN64) || defined(WINDOWS)
+    _locale_t locale;
+#else
+    locale_t locale;
 #endif
 } MdbHandle;