stty settings don't stick when invoked as a subprocess

[carenas]

Description / Steps to reproduce the issue

compile the following application in a non MSYS environment:

#include <windows.h>
#include <stdio.h>

int main(void)
{
        char buf[32];

        system("stty -echo");
        gets(buf);
        printf("INPUT: %s\n", buf);

        return 0;
}

A TCL example reported earlier in #3011

Expected behavior

no output while typing, like when build/run in an MSYS2 terminal or another OS

Actual behavior

terminal echo is active, calling GetConsoleMode() before and after the system() call confirms the mode hasn't changed

Verification

• I have verified that my MSYS2 is up-to-date before submitting the report (see https://www.msys2.org/docs/updating/)

Windows Version

MINGW64_NT-10.0-26100

Are you willing to submit a PR?

Yes