Filing this one for completeness in case the patch is forgotten about upstream, so we have some hope of remembering it. """ dup2 requires a <unistd.h> include. Fixes the following when diffing config.log when testing with a stricter compiler: ``` -warning: call to undeclared function 'dup2'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] +error: call to undeclared function 'dup2'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] ``` """ https://lists.gnu.org/archive/html/bug-bash/2023-02/msg00000.html
