scripts/coccinelle: add some more coccinelle tests

Add some useful static code analysis scripts for coccinelle
copied from the Linux kernel v4.14-rc8:

Warn on check against NULL before calling free.
scripts/coccinelle/free/ifnullfree.cocci

Detect superfluous NULL check for list iterator.
scripts/coccinelle/iterators/itnull.cocci

Check if list iterator is reassigned.
scripts/coccinelle/iterators/list_entry_update.cocci

Check if list iterator is used after loop.
scripts/coccinelle/iterators/use_after_iter.cocci

Find wrong argument of sizeof in allocation function:
scripts/coccinelle/misc/badty.cocci

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

scripts/coccinelle/free/ifnullfree.cocci

@@ -0,0 +1,59 @@
+/// NULL check before some freeing functions is not needed.
+///
+/// Based on checkpatch warning
+/// "kfree(NULL) is safe this check is probably not required"
+/// and kfreeaddr.cocci by Julia Lawall.
+///
+// Copyright: (C) 2014 Fabian Frederick.  GPLv2.
+// Comments: -
+// Options: --no-includes --include-headers
+
+virtual patch
+virtual org
+virtual report
+virtual context
+
+@r2 depends on patch@
+expression E;
+@@
+- if (E != NULL)
+(
+  kfree(E);
+|
+  kzfree(E);
+|
+  debugfs_remove(E);
+|
+  debugfs_remove_recursive(E);
+|
+  usb_free_urb(E);
+|
+  kmem_cache_destroy(E);
+|
+  mempool_destroy(E);
+|
+  dma_pool_destroy(E);
+)
+
+@r depends on context || report || org @
+expression E;
+position p;
+@@
+
+* if (E != NULL)
+*	\(kfree@p\|kzfree@p\|debugfs_remove@p\|debugfs_remove_recursive@p\|
+*         usb_free_urb@p\|kmem_cache_destroy@p\|mempool_destroy@p\|
+*         dma_pool_destroy@p\)(E);
+
+@script:python depends on org@
+p << r.p;
+@@
+
+cocci.print_main("NULL check before that freeing function is not needed", p)
+
+@script:python depends on report@
+p << r.p;
+@@
+
+msg = "WARNING: NULL check before freeing functions like kfree, debugfs_remove, debugfs_remove_recursive or usb_free_urb is not needed. Maybe consider reorganizing relevant code to avoid passing NULL values."
+coccilib.report.print_report(p[0], msg)