Fix for issue #202, regarding the lack of implementation of the localeconv method in some SDK's.

A macro named `ENABLE_LOCALES` was added and an option with the same name too in the CMakeLists.txt

cJSON.c

@@ -193,8 +193,12 @@ CJSON_PUBLIC(void) cJSON_Delete(cJSON *item)
 /* get the decimal point character of the current locale */
 static unsigned char get_decimal_point(void)
 {
+#ifdef ENABLE_LOCALES
     struct lconv *lconv = localeconv();
     return (unsigned char) lconv->decimal_point[0];
+#else
+	return '.';
+#endif
 }
 
 typedef struct