common: kill _supported_os

fstests only supports Linux, so get rid of this unnecessary predicate.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

common/rc

@@ -1456,24 +1456,6 @@ _supported_fs()
     _notrun "not suitable for this filesystem type: $FSTYP"
 }
 
-
-# tests whether $FSTYP is one of the supported OSes for a test
-#
-_supported_os()
-{
-    local h
-
-    for h
-    do
-	if [ "$h" = "$HOSTOS" ]
-	then
-	    return
-	fi
-    done
-
-    _notrun "not suitable for this OS: $HOSTOS"
-}
-
 # check if a FS on a device is mounted
 # if so, verify that it is mounted on mount point
 # if fstype is given as argument, verify that it is also