network: fix check for ambiguous lookup

network: fix check for ambiguous lookup

gcc -O2 complained:
../../src/conf/network_conf.c: In function 'virNetworkDefUpdateDNSSrv':
../../src/conf/network_conf.c:3232: error: 'foundIdx' may be used uninitialized in this function [-Wuninitialized]

It turned out to be a spurious warning (we didn't use foundIdx
unless foundCt was non-zero).  But in investigating that, I noticed
a worse problem: we were using 'if (foundCt > 1)', but since foundCt
was bool, it could never be > 1.

* src/conf/network_conf.c (virNetworkDefUpdateDNSHost): Use
correct type.
(virNetworkDefUpdateDNSSrv): Likewise, and silence compiler
warning.