Revert "fix -Wgnu-designator warnings"

Struct initialization using dot notation as in C99, but that happens to
not be valid C++, although apparently in C++11 it is valid. We'll need a
way to keep clang from throwing warnings at this initialization style,
either using some macros to detect the comiler environment, or perhaps
moving struct initialization to a C file rather than C++.

This reverts commit 6efc2b54d5ce85fcb4b66237b051bcbb5072e6a3.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
Merge pull request #812 from ceph/revert-struct-init

Revert "fix -Wgnu-designator warnings"