ssl: Remove shadowed variable in write retry path

ssl: Remove shadowed variable in write retry path

Commit 5f3db0d81132 "Fix false success on zero BIO write" introduced
a function-scope left variable while the app-buffer recovery block
already declared one.  This breaks builds using -Werror=shadow.

Assign the current buffer length to the existing function-scope variable
in the recovery block.  This preserves the previous re-read at that point
while eliminating the shadowed declaration.

Fixes: 5f3db0d81132 "Fix false success on zero BIO write"
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Andrew Dinh <andrewd@openssl.org>
Reviewed-by: Jakub Zelenka <jakub.zelenka@openssl.foundation>
Reviewed-by: Eugene Syromiatnikov <esyr@openssl.org>
MergeDate: Mon Aug  3 15:46:22 2026
(Merged from https://github.com/openssl/openssl/pull/32153)