I noticed this while working on qemuDomainGetBlockInfo.  Assigning
a bool value to an int variable compiles fine, but raises red flags
on the maintenance front as it becomes too easy to assign -1 or 2
or any other non-bool value to the same variable.

* cfg.mk (sc_prohibit_int_assign_bool): New rule.
* src/conf/snapshot_conf.c (virDomainSnapshotRedefinePrep): Fix
offenders.
* src/qemu/qemu_driver.c (qemuDomainGetBlockInfo)
(qemuDomainSnapshotCreateXML): Likewise.
* src/test/test_driver.c (testDomainSnapshotAlignDisks):
Likewise.
* src/util/vircgroup.c (virCgroupSupportsCpuBW): Likewise.
* src/util/virpci.c (virPCIDeviceBindToStub): Likewise.
* src/util/virutil.c (virIsCapableVport): Likewise.
* tools/virsh-domain-monitor.c (cmdDomMemStat): Likewise.
* tools/virsh-domain.c (cmdBlockResize, cmdScreenshot)
(cmdInjectNMI, cmdSendKey, cmdSendProcessSignal)
(cmdDetachInterface): Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>