common: drop HOSTOS

We effectively support only Linux these days, so drop most of the
special casing of HOSTOS.  We'll retain the simple check just in case
someone tries to run this on a different operating system.

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

common/rc

@@ -31,19 +31,13 @@ _math()
 
 dd()
 {
-   if [ "$HOSTOS" == "Linux" ]
-   then	
 	command dd --help 2>&1 | grep noxfer >/dev/null
-	
 	if [ "$?" -eq 0 ]
 	    then
 		command dd status=noxfer $@
 	    else
 		command dd $@
-    	fi
-   else
-	command dd $@
-   fi
+	fi
 }
 
 # Prints the md5 checksum of a given file
@@ -971,7 +965,7 @@ _scratch_mkfs_sized()
 
     local blocks=`expr $fssize / $blocksize`
 
-    if [ "$HOSTOS" == "Linux" -a -b "$SCRATCH_DEV" ]; then
+    if [ -b "$SCRATCH_DEV" ]; then
 	local devsize=`blockdev --getsize64 $SCRATCH_DEV`
 	[ "$fssize" -gt "$devsize" ] && _notrun "Scratch device too small"
     fi
@@ -1743,11 +1737,6 @@ _require_logdev()
 #
 _require_loop()
 {
-    if [ "$HOSTOS" != "Linux" ]
-    then
-	_notrun "This test requires linux for loopback device support"
-    fi
-
     modprobe loop >/dev/null 2>&1
     if grep loop /proc/devices >/dev/null 2>&1
     then
@@ -1761,11 +1750,6 @@ _require_loop()
 #
 _require_ext2()
 {
-    if [ "$HOSTOS" != "Linux" ]
-    then
-	_notrun "This test requires linux for ext2 filesystem support"
-    fi
-
     modprobe ext2 >/dev/null 2>&1
     if grep ext2 /proc/filesystems >/dev/null 2>&1
     then