qom: Use g_ascii_strcasecmp instead of strcasecmp

This is a change in semantics. g_ascii_strcasecmp() doesn't honour locale but strcasecmp() does. But this is OK for at least one reason: (1) QEMU always runs with the C locale so there's not an actual behaviour change here (2) we want the comparison on class names to be a plain ASCII one, not to do weird things with "I" in Turkish locales, so g_ascii_strcasecmp() is better as it's explicit about that Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Kostiantyn Kostiuk <kkostiuk@redhat.com> Link: https://lore.kernel.org/r/20260327134401.270186-3-kkostiuk@redhat.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>