idevice: add error checking to internal_ssl_write()
idevice: add error checking to internal_ssl_write()

Returning 0 bytes sent upon error causes an infinite loop
within the calling gnutls code. Returning -1 as an error
code allows gnutls to properly detect and recover.

kalev/libimobiledevice,kalev/libimobiledevice,upbit/libimobiledevice,libimobiledevice-win32/libimobiledevice,upbit/libimobiledevice,Tatsh/libimobiledevice,libimobiledevice-win32/libimobiledevice,upbit/libimobiledevice,libimobiledevice-win32/libimobiledevice,Tatsh/libimobiledevice,Tatsh/libimobiledevice,libimobiledevice/libimobiledevice,patweb/libimobiledevice,kalev/libimobiledevice,libimobiledevice-win32/libimobiledevice,Tatsh/libimobiledevice,libimobiledevice/libimobiledevice,patweb/libimobiledevice,patweb/libimobiledevice