Add -Wno-builtin-macro-redefined to compiler flags. (#17209)

This silences warnings about macros that are provided by the preprocessor/compiler itself being redefined. This is needed to silence warnings about _FORTIFY_SOURCE being redefined, which are being generated as we prefer a more aggressive value for it than what most distros provide by default. Without this change, the build is really noisy on many systems, and also fails when run with `-Werror`. It is also required long-term to allow for reproducible builds without throwing errors, as they need to redefine a number of macros provided by the preprocessor at build time.