For doubleinit.cocci, Coccinelle 0.2.4 requires a comma after ... in a
field list.  Coccinelle also now behaves gracefully when a definition is
provided for a virtual that doesn't exist, so there is no need for the
semantic patch code to check for this case.

Updated the documentation to reflect the fact that the best results will
now be obtained with Coccinelle version 0.2.4 or later.
Signed-off-by: NJulia Lawall <julia@diku.dk>

deref_null.cocci is moved to the 'null' directory
which contains other null related rules.
Signed-off-by: NNicolas Palix <npalix@diku.dk>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Add a Coccinelle file to identify the dereferences of NULL variables

This semantic patch identifies when a variable is known to be NULL
after a test, but it is still dereferenced later.
Signed-off-by: NNicolas Palix <npalix@diku.dk>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NMichal Marek <mmarek@suse.cz>