[LIBXC][POWERPC] use O_CREAT on open call for DTB_FILE

[LIBXC][POWERPC] use O_CREAT on open call for  DTB_FILE
This fixes a bug in the creating of the flat dev tree. If open is used
and O_CREAT not is specified, it will fail if the file has not already
been created. This patch will create the file if it does not exist
already. Which will allow for DomU creation.
Signed-off-by: Jerone Young <jyoung5@us.ibm.com>
Signed-off-by: Jimi Xenidis <jimix@watson.ibm.com>
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
--HG--
extra : transplant_source : Q%CA%40%88N%D8%25%B0%D7%FD%F8%1A%1E%07%8E2E%1BM%22