gcc/11: apply upstream fix 103910 so openjdk builds
Our openjdk derivations fail to build with `-march=opteron` (via
either `NIX_CFLAGS_COMPILE` or `hostPlatform.gcc.arch`). This was
fixed upstream in gcc12 but not carried back to gcc11:
https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=d243f4009d8071b734df16cd70f4c5d09a373769
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103910
Since gcc11 is still nixpkgs' primary compiler, this PR cherry-picks
the fix out of gcc12.
Unfortunately since `-march=` can be added after the `gcc11`
derivation is built we can't apply this patch conditionally (which
we don't usually do anyways).