Add support for QNX 7.1 with io-sock on x64

Signed-off-by: Florian Bartels <Florian.Bartels@elektrobit.com>

Author: flba-eb

std/Cargo.toml

@@ -139,7 +139,7 @@ test = true
 level = "warn"
 check-cfg = [
     'cfg(bootstrap)',
-    'cfg(target_arch, values("xtensa", "aarch64-unknown-nto-qnx710_iosock"))',
+    'cfg(target_arch, values("xtensa", "aarch64-unknown-nto-qnx710_iosock", "x86_64-pc-nto-qnx710_iosock"))',
     'cfg(target_env, values("nto71_iosock"))',
     # std use #[path] imports to portable-simd `std_float` crate
     # and to the `backtrace` crate which messes-up with Cargo list