testscripts/test_robind.sh: cleanup and make some fixes

Remove useless comments and abandon the operation which creates
a 500MB image-file. If user wants to run these tests, a big block
device should be specified by running runltp with -z option.

And we split tests in testscripts/fs_ro_tests into separate testcases,
keep one entry per test in runtest/fs_readonly

Using the interface provided by the shell library test.sh.

Delete fs_ro_tests, which is not used now.

Fix bashishm.

Signed-off-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
diff --git a/testscripts/Makefile b/testscripts/Makefile
index 870cf5c..c0cec15 100644
--- a/testscripts/Makefile
+++ b/testscripts/Makefile
@@ -28,7 +28,7 @@
 
 INSTALL_MODE		:= 00755
 
-INSTALL_TARGETS		:= *.sh fs_ro_tests
+INSTALL_TARGETS		:= *.sh
 
 MAKE_TARGETS		:=