fix 7 "make check" test failures in non-srcdir build

* tests/capabilityschematest: Define and use $srcdir.
* tests/domainschematest: Likewise.
* tests/interfaceschematest: Likewise.
* tests/networkschematest: Likewise.
* tests/nodedevschematest: Likewise.
* tests/storagepoolschematest: Likewise.
* tests/storagevolschematest: Likewise.

tests/capabilityschematest

 #!/bin/sh
 
-. ./schematestutils.sh
+: ${srcdir=.}
+. $srcdir/schematestutils.sh
 
 DIRS="capabilityschemadata xencapsdata"
 SCHEMA="capability.rng"

tests/domainschematest

 #!/bin/sh
 
-. ./schematestutils.sh
+: ${srcdir=.}
+. $srcdir/schematestutils.sh
 
 DIRS="domainschemadata qemuxml2argvdata sexpr2xmldata xmconfigdata xml2sexprdata"
 SCHEMA="domain.rng"

tests/interfaceschematest

 #!/bin/sh
 
-. ./schematestutils.sh
+: ${srcdir=.}
+. $srcdir/schematestutils.sh
 
 DIRS="interfaceschemadata"
 SCHEMA="interface.rng"

tests/networkschematest

 #!/bin/sh
 
-. ./schematestutils.sh
+: ${srcdir=.}
+. $srcdir/schematestutils.sh
 
 DIRS="../src/network networkxml2xmlin networkxml2xmlout"
 SCHEMA="network.rng"

tests/nodedevschematest

 #!/bin/sh
 
-. ./schematestutils.sh
+: ${srcdir=.}
+. $srcdir/schematestutils.sh
 
 DIRS="nodedevschemadata"
 SCHEMA="nodedev.rng"

tests/storagepoolschematest

 #!/bin/sh
 
-. ./schematestutils.sh
+: ${srcdir=.}
+. $srcdir/schematestutils.sh
 
 DIRS="storagepoolxml2xmlin storagepoolxml2xmlout"
 SCHEMA="storagepool.rng"

tests/storagevolschematest

 #!/bin/sh
 
-. ./schematestutils.sh
+: ${srcdir=.}
+. $srcdir/schematestutils.sh
 
 DIRS="storagevolxml2xmlin storagevolxml2xmlout"
 SCHEMA="storagevol.rng"