sftp: Handle short reads of sftp_async_read().
sftp: Handle short reads of sftp_async_read().

sftp_async_read() and sftp_async_read_begin() assume that the whole read
will be successful but when this is not the case, the offset will be
wrong.

Signed-off-by: Andreas Schneider <5be00ddc76278cf6077f5047ca3384a88460c671@cryptomilk.org>

nviennot/libssh,mwgoldsmith/ssh,elastichosts/libssh,wangshawn/libssh,kedazo/libssh,elastichosts/libssh,mwgoldsmith/ssh,taikoo/libssh,bigcat26/libssh-mod,kedazo/libssh,pouete/libssh,wangshawn/libssh,mwgoldsmith/libssh,wangshawn/libssh,DouglasHeriot/libssh,robxu9/libssh,pouete/libssh,pouete/libssh,sebadoom/libssh,bigcat26/libssh-mod,robxu9/libssh,Distrotech/libssh,DouglasHeriot/libssh,bigcat26/libssh-mod,nviennot/libssh,jt1/honeypot-libssh,robxu9/libssh,sebadoom/libssh,nviennot/libssh,pouete/libssh,mwgoldsmith/ssh,kedazo/libssh,Distrotech/libssh,Distrotech/libssh,sebadoom/libssh,kedazo/libssh,mwgoldsmith/libssh,sebadoom/libssh,DouglasHeriot/libssh,jt1/honeypot-libssh,bigcat26/libssh-mod,mwgoldsmith/libssh,taikoo/libssh,wangshawn/libssh,taikoo/libssh,Distrotech/libssh,DouglasHeriot/libssh,mwgoldsmith/libssh,jt1/honeypot-libssh,nviennot/libssh,mwgoldsmith/ssh,jt1/honeypot-libssh,elastichosts/libssh,robxu9/libssh,taikoo/libssh