fstests: Make ./new work for non-root user

Currently 'new' script sources common/config which tries to find
mkfs and fails if not found (which is likely for non-root user).
This is inconvenient as development usually does not happen as root.
In fact the vast majority of setup in common/config and common/rc is
not necessary for 'new'. Split out the necessary bits into new
common/test_names and use it in 'new'. Cleanup common/rc and
common/config now that they're only used from 'check' and 'setup'.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

check

@@ -331,10 +331,10 @@ while [ $# -gt 0 ]; do
 	shift
 done
 
-# we need common/config, source it after processing args, overlay needs FSTYP
-# set before sourcing common/config
-if ! . ./common/config; then
-	echo "$iam: failed to source common/config"
+# we need common/rc, that also sources common/config. We need to source it
+# after processing args, overlay needs FSTYP set before sourcing common/config
+if ! . ./common/rc; then
+	echo "check: failed to source common/rc"
 	exit 1
 fi
 
@@ -374,13 +374,6 @@ elif [ -z "$GROUP_LIST" ]; then
 	GROUP_LIST="auto"
 fi
 
-# we need common/rc
-if ! . ./common/rc
-then
-    echo "check: failed to source common/rc"
-    exit 1
-fi
-
 if [ `id -u` -ne 0 ]
 then
     echo "check: QA must be run as root"