Bug#983436: i386-cpuinfo.h missing in gcc-10-plugin-dev

["Trent W. Buck" <trentbuck@gmail.com>]

This bug means I cannot enable Linux kernel hardening features,
when using Debian 11's gcc and backport kernel.

    GCC_PLUGIN_RANDSTRUCT "Randomize layout of sensitive kernel structures"
    https://github.com/torvalds/linux/blob/master/scripts/gcc-plugins/Kconfig#L49

    GCC_PLUGIN_STACKLEAK "Poison kernel stack before returning from syscalls"
    https://github.com/torvalds/linux/blob/master/security/Kconfig.hardening#L152

    GCC_PLUGIN_STRUCTLEAK
    https://github.com/torvalds/linux/blob/master/security/Kconfig.hardening#L4

The specific kernel I tested was

    https://snapshot.debian.org/archive/debian/20211015T150402Z/pool/main/l/linux/linux_5.14.9-2%7Ebpo11%2B1.dsc