[$] Two security improvements for GCC

It has often been said that the competition between the GCC and LLVM
compilers is good for both of them. One place where that competition
shows up is in the area of security features; if one compiler adds a way to
harden programs, the other is likely to follow suit. Qing
Zhao's session at the 2021
Linux Plumbers Conference told the story of how GCC successfully played
catch-up for two security-related features that were of special interest to
the kernel community.