[C++][Flight] Avoid undefined behavior with gRPC memory optimizations #21105
Description
Because the Write function and other on ServerWriter and ClientReader are declared virtual, some compilers may not behave in the way we want.
Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm
PRs and other links:
Note: This issue was originally created as ARROW-4558. Please see the migration documentation for further details.