The function does not return the same value as snprintf() normally does,
so readers may be mislead into thinking the code works differently than
it actually does. A different function name makes this easier to detect.
Reported-by: Tomas Hoger
Assisted-by: Daniel Gustafsson
Fixes#3296Closes#3297
Modifying the locale with environment variables doesn't work for native
Windows applications. Just disable the test in this case if the decimal
separator is something different than a point. Use a precheck with a
small C program to achieve that.
Closes https://github.com/curl/curl/pull/2786
