util: Fix UB in SetStdinEcho when ENOTTY

contrib/valgrind.supp

@@ -14,12 +14,6 @@
 # Note that suppressions may depend on OS and/or library versions.
 # Tested on aarch64 and x86_64 with Ubuntu Noble system libs, using clang-16
 # and GCC, without gui.
-{
-   Suppress uninitialized bytes warning in compat code
-   Memcheck:Param
-   ioctl(TCSET{S,SW,SF})
-   fun:tcsetattr
-}
 {
    Suppress leaks on shutdown
    Memcheck:Leak