* src/qemu_driver.c: Use virSetCloseExec and virSetNonBlock,
rather than qemuSet* functions.  Suggested by Daniel P. Berrange.
* src/util.c (virSetCloseExec): Publicize.
* src/util.h (virSetCloseExec): Declare
* src/libvirt_private.syms: Add virSetCloseExec.