Fix "adb sync" (and "adb push") error reporting.

This patch ensures that we read any error response from the server if the
server closes the connection. Unfortunately, that's not sufficient to ensure
that we always see the server's error message --- sometimes the data just
gets thrown away because we keep writing without reading. Setting SO_LINGER
avoids this.

Bug: http://b/25230872
Change-Id: I96c019cc72bd139198de79bf29e6536cc462c20f