Fix EOF handling in AdbClient (take 2)

Summary:
AdbClient would spin in a loop in ReadAllBytes in case the remote end was closed before reading
the requested number of bytes. Make sure we return an error in this case instead.

Reviewers: ovyalov

Subscribers: tberghammer, danalbert, lldb-commits

Differential Revision: http://reviews.llvm.org/D19916

llvm-svn: 268617