[sanitizer] Fix msan test build on FreeBSD after 7afdc89c2054

This commit accidentally enabled fgetgrent_r() in the msan tests under
FreeBSD, but this function is not supported. Also remove FreeBSD from
the SANITIZER_INTERCEPT_FGETGRENT_R macro.

GitOrigin-RevId: e056fc6cb676f72d5b7dfe7ca540b3275bd1a46f
2 files changed