Makefile: include rocksdb in dist tarball always

Signed-off-by: Sage Weil <sage@redhat.com>
configure: enable static rocksdb if check and c++11

Signed-off-by: Sage Weil <sage@redhat.com>
add rocksdb bz2 dep

Signed-off-by: Sage Weil <sage@redhat.com>