tests: don't alter state in $HOME

Diego reported a bug where virsh tries to initialize a readline
history directory during 'make check' run as root, but fails
because /root was read-only.

It turns out that I could reproduce this as non-root, by using:

mv ~/.virsh{,.bak}
chmod a-w ~
make check -C tests TESTS=int-overflow
chmod u+w ~
mv ~/.virsh{.bak,}

* tests/int-overflow: Don't trigger interactive mode.
Reported by Diego Elio Pettenò.

tests/int-overflow

@@ -14,9 +14,9 @@ fi
 . "$srcdir/test-lib.sh"
 
 echo "error: failed to get domain '4294967298'" > exp || fail=1
-echo domname 4294967298 | $abs_top_builddir/tools/virsh --quiet \
+$abs_top_builddir/tools/virsh --quiet \
     --connect test://$abs_top_srcdir/examples/xml/test/testnode.xml \
-    > /dev/null 2> err || fail=1
+    'domname 4294967298; quit' > /dev/null 2> err || fail=1
 diff -u err exp || fail=1
 
 exit $fail