When trying to build with latest libcacard-2.5.1, I hit the
following error:

In file included from hw/usb/ccid-card-passthru.c:12:0:
/usr/include/cacard/vscard_common.h:26:2: error: #warning "Only <libcacard.h> can be included directly" [-Werror=cpp]
 #warning "Only <libcacard.h> can be included directly"

While it was fixed in libcacard upstream (so that individual
files can be included directly), it doesn't make much sense.
Let's switch to including the main libcacard.h and also require
at least libcacard-2.5.1 which introduced it. It's available
since late 2015.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 3c36db1dc0702763ebb7966cc27428ed67d43804.1522751624.git.mprivozn@redhat.com

[ kraxel: fix include path ]
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>