Forward-port from 2.0

[NIIBE Yutaka]

Scanning log of STABLE-BRANCH-2-0, I forward-ported following
change to master (2.1).

commit 5798673156a66f4c39e1d34e358b03539194d57c
Author: Andreas Schwier <andreas.schwier at cardcontact.de>
Date:   Fri Jul 18 18:22:26 2014 +0200

    scd: Allow for certificates > 1024 with PC/SC.

    * scd/pcsc-wrapper.c (handle_transmit): Enlarge buffer to 4096 too
    allow for larger certificates.
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