Prevent metadata corruption in the race conditions between
FOP->open() and FOP->link().

Problem: crypt_open() modifies @local->format, which is used
by crypt_link() to store the updated metadata string on disk.
This results in metadata corruption.

Fixup: Don't modify @local->format by FOP->open(). Instead
modify a local copy, allocated in the low-level meta-data
handler open_format_v1().

Change-Id: I046bb39ddefc33afe59c8d3b1a2fa798298f8499
BUG: 1157839
Signed-off-by: Edward Shishkin <edward@redhat.com>
Reviewed-on: http://review.gluster.org/8982
Reviewed-by: Emmanuel Dreyfus <manu@netbsd.org>
Tested-by: Emmanuel Dreyfus <manu@netbsd.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>