domain_conf.c: Initialize arrVar and cntVar

domain_conf.c: Initialize arrVar and cntVar

Some ancient gcc fails to see the variables are initialized in a
separate function and a false positive is produced:

cc1: warnings being treated as errors
conf/domain_conf.c: In function 'virDomainChrGetDomainPtrs':
conf/domain_conf.c:10342: error: 'arrVar' may be used uninitialized in this function [-Wuninitialized]
conf/domain_conf.c:10343: error: 'cntVar' may be used uninitialized in this function [-Wuninitialized]
conf/domain_conf.c: In function 'virDomainChrInsert':
conf/domain_conf.c:10362: error: 'arrPtr' may be used uninitialized in this function [-Wuninitialized]
conf/domain_conf.c:10363: error: 'cntPtr' may be used uninitialized in this function [-Wuninitialized]
conf/domain_conf.c: In function 'virDomainChrRemove':
conf/domain_conf.c:10374: error: 'arrPtr' may be used uninitialized in this function [-Wuninitialized]
conf/domain_conf.c:10375: error: 'cntPtr' may be used uninitialized in this function [-Wuninitialized]

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>