In blktap2 MEMSHR_DIR is used before it is set. This removes the
required -D_GNU_SOURCE from CFLAGS, its used as option for -I
Fix this by moving memshr related flags to the place where its actually
used.
The failure is a missing O_DIRECT define.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>