Commit c29e6d48 cause build failure on RHEL-6:

../../src/qemu/qemu_capabilities.c: In function 'virQEMUCapsIsValid':
../../src/qemu/qemu_capabilities.c:4085: error: declaration of 'ctime'
shadows a global declaration [-Wshadow]
/usr/include/time.h:258: error: shadowed declaration is here [-Wshadow]
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>