common/exechelp: Add general pipe function.
* common/exechelp-posix.c (gnupg_create_pipe): New function. * common/exechelp-w32.c (INHERIT_{READ,WRITE,BOTH}): New macros. (create_inheritable_pipe): Generalize so that both ends can be inherited. (do_create_pipe): Rename argument accordingly. (gnupg_create_{in,out}bound_pipe): Use new flags. (gnupg_create_pipe): New function. (gnupg_spawn_process): Use new flags. * common/exechelp-w32ce.c (gnupg_create_pipe): New stub. * common/exechelp.h (gnupg_create_pipe): New prototype.
- Signed-off-by: Justus Winter <justus@g10code.com>